GUBIN, POLAND -- The regular Saturday morning German invasion was at full roar.

In the middle of the mostly fair-haired horde, a bearded Pole named Jerzy Iwaniec stood beside his table of smoked eels.

Since the East Germans began raiding this border town last July -- newly armed with marks, the strongest currency in Europe, that they had acquired in the three months since their country's economic union with West Germany -- Iwaniec has parlayed eels into a handsome living.

His philosophy is to treat Germans courteously, wish them "Guten apetit" and charge them 50 to 100 percent more than he charges Poles.

"You can sell anything. A lot of Poles have made a lot of money," Iwaniec explained as he wrapped up another eel for another German.

In the post-Communist era, as socialist subsidies wither and the profit motive gathers steam, the people of the defunct Eastern Bloc have had to improvise to make ends meet. Just such an improvisational performance occurs here on weekends along the Polish-German border.

On Saturday mornings, about a half-million East German shoppers head east across the border formed by the Oder and Neisse rivers. There to greet them, with smiles on their faces and calculators in their hands, are thousands of traders from all over Poland.

In the sprawling open-air market that has taken over most of central Gubin, German gutturals crash incomprehensibly against Polish sibilants. In the linguistic snarl, sales are concluded with hand signals and offers scrawled on paper bags. The sweet smoke of roasting Polish kielbasa mingles with the ghastly discharge of East German Trabant cars. All sales are final.

On a recent Saturday, an East German policeman from the town of Calau stood away from the crowds and took off his pants. He squirmed and wriggled in the brisk September wind, trying to stuff his ample self into a pair of Polish blue jeans. Goose bumps erupted on his pink flesh, and his wife opined as how the jeans might be too tight.

In front of a table laden with Albanian cigarettes, a transaction in the new European economic order was taking place.

"I want to sample one," said Kluse Rudi, a truck driver from the East German town of Koethen. He gestured at the Albanian brand, Gent. He spoke German.

"No! Take the whole carton. Where can you get cheaper cigarettes?" said Andrzej Jaworski, a trader from the Polish city of Lodz. He spoke Polish.

The German and the Pole, at some primordial economic level, understood each other. The German forked over six marks, about $3.80. The Pole stuffed away his earnings and smiled beatifically, awaiting more Germans.

East Germany, soon to be swallowed up in a unified Germany, has become painfully expensive for residents accustomed to state subsidies that were eliminated when the two Germanys merged their economies on July 1.

By German standards, Poland is still wonderfully cheap. Everything from bread to cigarettes, bluejeans to smoked eels costs about half what it costs in East Germany. And newly capitalist Poland is frantic to sell.

Polish traders have a reputation for knowing how to make quick money. For decades, they took advantage of Communist subsidies, buying cheap in one country and selling dear in the next. Hundreds of thousands of Poles traveled and traded for a living. In the process, they acquired an unsavory regional reputation as sharpies.

The East German government restricted Polish access to subsidized East German goods. "The opinion in East Berlin still is that Poles should stay home and not do all these speculations," said Peter Kauffmann, an East Berliner who drove to Poland last weekend to buy some cheap jeans.

Now, some Poles see a fine irony in having Germans, starving for bargains, come to them. "The foreign currency we spent in Berlin in the past is finally coming back to us," said Janosz Szymanski, who supplements his salary as an engineer by selling jogging outfits to Germans at double his cost.

Some East Germans have even acquired habits traditionally associated with Poles. Earlier this month, Polish border guards detained an East German who was attempting to go home with "personal goods" that included 600 children's jackets, 80 adult jackets, 100 pairs of pants and 25 million Polish zlotys.

Despite a few such spoilsports, the Polish government could not be more delighted with the German invasion. After its post-Communist leaders instituted "shock therapy" economic reforms at the beginning of this year, Poland has struggled to cope with a recession that has triggered a 30 percent fall in living standards and put nearly 900,000 people out of work,

"Listen, I think it's a terrific opportunity," said Zygmunt Janczyk, a spokesman for the Customs Office. "One month ago I appealed on television encouraging individuals, tradesmen, private and state farms, cooperatives, etcetera to go west. I said, 'Go there and do business, because local people can't handle it.' "

Poles have needed no governmental help in sniffing out the potential of Germans laden with hard currency. Traders drive all night to set up their stalls by 9 a.m. on Saturdays, when the Germans start rolling into Gubin and other border towns. Having heard that East Germans will buy anything, some Poles come to the border with an eclectic mix of merchandise.

The range of goods on sale last weekend in Gubin and the nearby border town of Slubice included frozen chickens, ice skates, barbecue sauce, Russian gold necklaces, Christmas tree bulbs, lawn chairs, poppy-seed cake, Taiwanese high-top basketball shoes and artificial stuffed deer heads with plastic antlers.

"Germans like these artificial deer heads. I sold 15 in one hour," said a woman from the Polish town of Zielona Gora.

There is, however, a sticking point in this post-Communist tale of free trade.

The West German government has announced that after unification on Wednesday, it will require visas of all Poles traveling to Germany. The visa restrictions will not apply to Hungarians or Czechoslovaks.

The Warsaw government, in an apparent sign that it sees this policy as discriminatory and intends to get even, announced last week that it will impose similar visa restrictions on all Germans traveling to Poland.

"On the one hand, there is much talk about freedom of travel and freedom in general, while the practice is different with regard to Poland," Foreign Minister Krzysztof Skubiszewski grumbled last week.

"It is not a good beginning of the new relationship with the united Germany," said government spokesman Malgorzata Niezabitowska.

What effect the new visa rules will have on the border booms is unclear. Until Wednesday, East Germans can enter Poland by simply showing their identity cards.

The Polish government, seemingly anxious not to kill off a much-needed business opportunity, has asked for urgent negotiations with Bonn on the issue. There is a strong likelihood that visas for Germans planning to shop in Poland will be relatively easy to obtain.

Authorities in several Polish border towns made urgent appeals to Warsaw this week for visa-free passage. An open letter to Minister of Labor Jacek Kuron was published Thursday on the front page of Poland's largest daily newspaper, Gazeta Wyborcza. It pleaded with Kuron not to allow the border boom to die:

"Neither in mining nor in metallurgical industry have I seen people working as hard to make their living. . . . These people make it possible to sell output surplus and contribute millions of German marks to the country."

An estimate in Gazeta Wyborcza this week said that the 10 million Germans living within 60 miles of the Polish border might reasonably be expected to spend about $6 billion in Poland -- the sum of the country's Western exports.

Even if they have to buy visas, tens of thousands of former East Germans, stung by the cost of living in a unified Germany, are likely to continue shopping in Poland on weekends. Since the announcement that visas will be necessary, Polish consulates in East Germany have been besieged with applicants.

"For me the price of living has doubled," said Uwe Wladasch, a computer engineer who lives across the German border in the city of Frankfurt on Oder. "I come to buy bread. I can't say I ever thought I would want to do this in Poland."