The two buses rolled steadily at 60 miles per hour along the East German autobahn, heading west.

Inside each bus, 37 passengers sat silently. Just hours earlier they had all been "political prisoners" in jails throughout communist East Germany and no one yet dared believe, with certainty, that they were in fact being ransomed - set free for money paid quietly by the West German government.

A young woman passenger, a doctor, idly fingers the upholstery and chrome ashtray on the back of the seat facing her. The material was plastic but, she would later recall, it felt rich, like leather, not like an East German bus felt. It was then that she first believe it was real and he would soon be in the West.

Just before reaching the border, the bus pulls into a roadside rest area. Parked there is a shiny, beige-colored Mercedes-Benz automobile - perhaps the ultimate status symbol in West Germany but one that is never seen in the East with East German license plates.

The owner gets on the bus - an urban-looking, middle-aged man with glasses, wispy, light-brown hair, expensively tailored Western-styled clothes, a tell-tale heavy gold wrist-watch and a diamond ring. Though none of the passengers had ever met him before, they all knew who he was.

He is their lawyer, 53-year-old East German Dr. Wolfgang Vogel - one of the most intriguing yet private figures ever to emerge from the twilight world of postwar divided Germany into one of the most bizarre of modern businesses - the official, government-approved selling and trading of people.

In the past 15 years or so, about 14,000 people have been quietly bought out of East Germany jails by the Bonn government at a cost unofficially estimated at almost $500 million, mostly in hard Western cash but also in scarce products ranging from fruit to fertilizer.

Many of those ransomed are people who have asked too often or tried too hard, to get out of a country whose exits to the West have been sealed since 1961 to all but old-age pensioners, athletes and critics of the regime. Some are dissident trade unionists or clergymen. Some have been caught trying to help others escape.

The average price for what one American intelligence agent once called "East Germany's greatest cash crop" is now about $35,000 per person. But to buy the freedom of a doctor or professor might cost as much as $75,000 while an ordinary working-man prisoner might cost about $15,000.

Only a tiny fraction are spies, and the important ones tend to be traded rather than sold. Secret Operations

In 1962, it was Vogel who stood near the Potsdam Bridge in Berlin while Soviet spy Col. Rudolf Abel and U-2 pilot Francis Gary Powers crossed over in a swap he helped arrange.

On May 1, it was Vogel's beige Mercedes, this time with his wife at the wheel, that picked up American student Alan Van Norman - jailed for trying to help people escape - at a deserted East Berlin parking lot and whisked him through the city's dividing wall to the West while her husband was enroute from Washington with convicted Soviet spy Robert G. Thompson.

In between, there have been thousands of faceless others: Most of them come out by bus. Some come in more dramatic circumstances, perhaps at night in the back seat of Vogel's familiar car, being waved through the barricades, tank traps, barbed wire and spotlights of one of the less-used Berlin Wall crossing points.

Even for hardened tourists, driving across the East-West border at night can still provide the inevitable comparison with spy movies, with high-booted police rolling mirrors under the car and shoving long rods into the gas tank to see if it is filled with gasoline or people.

For many years, the ransom operations were secret. They still are in many respects. But in the past few years, stories have leaked out and people have talked, though anonymously.

Most recently, however, the curtain of secrecy has been raised much further with the publication here of the first book on the subject. "Ransom - Human Traffic in Germany," by French television correspondent Michel Meyer, who has been based in Germany for six years.

Most importantly, Meyer's book includes a lengthy interview with both Vogel and his West German counterpart, lawyer Juergen Stange, made in December 1976, that constitutes not only one of the rate times Vogel has talked for publication but is believed to be the last time he granted an interview.

It was the dramatic and highly publicized spy swaps that first brought even the shadowy image of Vogel to the attention of the Western public. But as the veil has lifted on his role in the ransoming of political prisoners, serious moral questions have been asked of both East and West German officials.

Vogel clearly is a clever man who occupies an extraordinary, perhaps unique, place in East Germany. He is one of only about a dozen private lawyers in East Germany, is a close confidant of East Germany Communist Party chief and ruler Erich Honecker, has a permanent visa to move back and forth between East and West, and carries on additional sensitive chores in the West for the Honecker government.

He has survived in these East-West pursuits for many years where others are believed to have enventually either failed or defected and has has been honored by East Berlin for his efforts.

He obviously lives far better than many top government functionaries, has two daugthters in Western universities - one of whom has an Amrican diplomat as a godfather - and also seems clearly to have acquired some wealth. Moral Questions

But in recent years, publicity about ransoming has raised questions about Vogel's role in human slave trade and the grim business of selling people, jailed on what to Westerners are unjustified counts to begin with, for hard cash.

"Such statements hurt and anger me," Vogel told Meyer, "especially if I get attacked personally, called a playboy, a privileged person, and it is inferred that I have Swiss bank accounts. What I do, along with Juergen Stange, gets twists and presented as conspiratorial. But I am convinced that we have done well for the citizens of both German states . . . both states have equally profited," an assessment Stange says he agrees with.

Vogel explains that to understand why payment for people is justified one has to understand the "political and Marxist process and attitude by which derelicts are judged in a socialist state. They are judged by the damage they cause to the social system and that of course is a thinking process foreign to all capitalistic countries."

In effect, Vogel argues that if it costs $75,000 to educate a doctor in East Germany who then goes and damages the socialist system and wants to leave, the state can rightfully ask to be reimbursed.

"The basic conception, that these derelicts can be compensated for materialistically, is the real, and the only, background of these exchange processes," he says.

Besides, he adds, "Our action also contributes to detente between East and West. Every spy, refugee or dissident whom we exchange means one less problem, one less bit of tension between the two German states."

"Who is normally better?" he asked rhetorically in an interview a few years earlier, "He who buys or he who sells?"

"Kennedy came here and said he was a Berliner and the Americans used to float balloons over the wall. But all of this achieved nothing. I, on the other hand, perform a humanatarian service by which everyone benefits."

Vogel, who is not a Communist Party Member but describes himself as a Marxist and a humanist, estimates that all told, the barter business has touched the lives of some 20,000 people when reunited families are included.

He and Stange, whom Meyer calls "the St. Bernards of the Elbe," a reference to the river that forms part of the border between East and West, both believe that the trade will continue as long as it is in the interests of both states. Best to Keep Quiet

But Vogel warns that "it could come to an end if the German Democratic Republic has the feeling that the exchange is being taken advantage of and exploited by Western propaganda against the East," calling attention to the human slave trade descriptions sometimes used.

It explains why perhaps both sides are not seeking any publicity now. "Please understand, it's best to keep quiet now," Vogel said last week in response to a request for an interview. Stange said he was unable to get the Bonn government to release him from his "liability to silence."

One other reason may be rumors of a Vogel involvement in a possible swap for Soviet dissident Anatoly Scharansky.

As for the West Germans, Strange says, "For us, the reasons are much more practical. We use every means possible to help people. To some, that may look immoral. But philosophy doesn't help us and it doesn't help those suffering" in jail.

"We are really like rope-dancers," Strange adds, on a line strung between two countries of different systems and where sometimes it may take years to get a prisoner freed before he can be brought to the West and given citizenship.

But even for Bonn, the growing public awareness of the trade is raising questions. In the immediate aftermath of World War II and during the ensuing Cold war, it was clear that there was enormous suffering in both Germanies and perhaps especially in the East. But now, even the East is, by communist standards, reasonably prosperous and the element of slave trade is becoming harder to keep from popping up.

In the past few years, roughly 1,500 prisoners have been ransomed annually, with Vogel and Strange swapping lists first to see who is available and who is wanted and to assure Bonn, at least, that they are not ransoming common criminals.

Usually twice a month, the buses make their runs, crossing the border near Herleshausen, switching license plates and drivers, and picking up their human cargo at Karl-Marx Stadt, where the prisoners are brought from scattered jails to a central pick-up point.

The money to pay for it is believed spread through a dozen Bonn ministries, much the way the U.S. CIA budget is hidden in Washington.

The question of who started it yields conflicting finger-pointing by Vogel and the West Germans.

What is now reasonably well documented, however, is that is started during the 1963-64 period, at the height of the Cold War and at an especially bad time for East Germany. A Test at the Wall

In 1961, East Germany sealed off its borders to the West and built the Berlin Wall to stop a humiliating and potentially economically fatal hemorrage of millions of residents fleeing to the West. Among other things, the the wall separated the offices of Vogel and Strange.

By 1962, Vogel was known because of the Abel-Powers swap. Soon after, the prospect of swapping lots of people was raised privately and, as a test of whether Vogel could deliver people that nobody knew about, the West German Evangelical Church, which had kept open secret channels of communcations and money to the Protestant Church in the East, provided names and a contact for the first dramatic exchange of people for money.

In a crowded East Berlin elevated train station, under the eyes of dozens of discretely posted security police a church representative handed over eight packets of money while eight prisoners were delivered, one by one, and allowed to move to the West on the rail line.

Other names came from the Red Cross. Later, the lists and exchanges grew into the hundreds. In an effort to make sure the money was being pocketed and was being used to help people in the East, in many cases payments were made in goods that could be checked later to see if they showed up in marketplaces.

In the years since then, Vogel has been a central figure in East-West dealings, yet always in the back-ground and always puzzling to those who try to figure out what really motivates him.

All countries have people like me," Vogel told Meyer, to handle some of the unorthodox things that governments get involved with.

Since March 1954, I have been a lawyer and I honestly consider myself an expert. I have earned well and am now earning well. But that has been the case for a long time and" he claims, "it has nothing to do with my role in prisoner exchange."

Though Vogel probably has benefited financially from his quasi-governmental role, those in the West who know him best - though not well - tend to doubt that Vogel does what he does just for the money. His free access to the West would have allowed him to defect years ago and his skills would undoubtedly have carried him to a high place in Western corporations or business.

So what makes him tick?

Some clues may lie in his background. He is a trader and he was born in Leipzig, an East German city that for centuries was a traditional trading crossroad for all of Europe. It still is the site of the semiannual Leipzig fair. the largest trade show in communist Eastern Europe.

His family came from Silesia in the northeast of Germany where he was born in 1925. They were forced to flee the region, along with millions of other germans, into Germany's more central heartland when advancing Soviet armies moved in and a postwar treaty yielded the area to Poland. So perhaps who either are displaced or who at least feel displaced.

Undoubtedly, there is an element of humanitanunism mixed into Vogel's thoughts, a feeling that both people and governments are being satisfied.

Perhaps the largest chunk of explanation, however, lies in Vogel's position within East Germany.

East Germany is kind of a gray place. There is relative prosperity in comparsion with the rest of the Soviet block, but it is a dull kind of prosperity.

Nevertheless, considering the ravaged state of East Germany right after the war and the fact that the Soviets, unlike the West, took more out of the East economically than they put into it. East Germans today have quite a bit to be proud of. The country has been built up enormously and Vogel reflects some of that pride.

If the walls and border fences came down tomorrow, clearly millions would flee. But many more millions probably would not.

The biggest and most politically explosive issue in East Germany today is that its citizens can't travel to the West. Vogel can. He can satisfy his taste for mod clothes easily. His office in Berlin's suburbs are appointed with fine furnishings and he can afford to indulge his fondness for collecting antique watches.

Though East Germany is supposed to be a classless society, the top officials live better than most, as in other communist bloc states. But the ones who live best are those who must travel between East and West because if they didn't live well at home, the government seems to believe, they might not come back because they have seen the other side.

So, in many places in East Germany, one can see fine homes occupied mostly by people who travel - well-known writers, trade officials and Vogel.

In effect, Wolfgang Vogel has the best, most exciting job in East Germany, and there really seems no reason for him to leave or to stop.

Today, when Vogel and Stange board a departing bus. Vogel reminds the passengers how delicate and difficult these negotiations remain and warns them not to speak about their experiences in the East - especially to Western newsmen - because if these negotiations are exploited for political reasons it could bring the flow to an end.

Sometimes the two men try to break the inevitable tension on each bus by slipping a chocolate bar into a passenger's hand or a 100-Deutsche mark note into a pocket. It is the final, perhaps unwitting, double symboy of a very strange business.