They come by the thousands every four years, each an inaugural horde reflecting a special spirit and style, and this Reagan bundh of 1981 brings its own unmistakable stamp.

Mink has come out of the closet. The only thing liberal about their limousines is the unending number. They are overwhelmingly white and middle-class. Many are monied -- have to be, at today's prices -- and they epitomize the true believers of American politics.

To a degree unseen at recent inaugurals, ostentation has been their hallmark this week. From it all, the uninitiated might be deluded into believing there are no more Harlems, no more migrant lettuce pickers, no more economic pinch.

"This is what America's all about. . . . It looks like a bunch of people who want to get back to what America really means," said one of their number, Agustin G. Prado, a Cuban-born businessman from Culver City, Calif.

Those southern populists in blue jeans and flannel shirts who had their day four years ago would disagree, no doubt, but they had their day. For now, that style is gone. Goodbye, Willie Nelson. Hello, Sinatra. "These people have waited a long, long time and they're rfeady to explode.But they do it quietly," said Don Fields, a young black businessman, a recent Republican convert who attended Jimmy Carter's inauguration as a Democrat. "The Carter people were loud and explosive. These people celebrate with implosion. They don't show a lot of emotion. But they feel it inside."

The Reaganites' private planes sat wing to wing at National Airport. Some of the imported limos were as big as buses. A group of Indiana Republicans came by rail, in the opulent private car once owned by J. p. Morgan, fat cat nonpareil.

The clerks, cabbies and truck drivers, the heroes of the factory and sales, counter to whom the new president referred in his inaugural address were in scant evidence for these festrivities that began last week.

But put aside the stereotypes and the instant impressions. What was in the air of Inauguration Day, 1981, was the spirit of a no-nonsense "new beginning" -- the official theme, in fact.

True believers. The heart of John V. Amero, a retired Navy nuclear submarine inspector from Rochester, N.H., caught it well. "I haven't been so enthusiastic about a candidate since Harry Truman," he said.

There was striking contrast between a retired bureaucrat and his limousine-riding brethren, but the common cord between them was that very Republican, very Reaganesque belief that the country has gone to hell, thanks to liberal Democrats and Washington.

Inaugurals always are tribal rituals, acts of cleansing the old with the new. If Kennedy's celebrated a new generation's rise to power and Carter's the resurgence of the South, then Reag an's may be the reassertion of stolid middle America and its values.

Everyone felt it, though these were emotions difficult to articulate. Ronald Reagan's landslide election had proven it. Yesterday, his followers reveled in it.

Here is William Boyd, conservative, San Francisco lawyer, married to a Reagan volunteer: "It's sort of an expresion of joy. Finally, something we've worked for has come to flourish. It's like a flower coming up in the spring."

Here is Roland Wright, rancher from Moore, Mont., and his wife June, a Reagan worker: "We're here because it's the first time we ever participated in politics. . . . We don't ask special privileges or grants. We just hope enough can be done in the next six months."

And Betty Anglin, GOP converntion delegate from Dodge City, Kan., chairman for the Reagan campaign in western Kansas: "Ronald Reagan is down to earth. He'll bring the country back to its senses."

Oh, such irony. This inaugural was the costliest in history -- upwards of $8 million -- and it was made possible only because these Reagan people could pay the price, which was not necessarily synonymous with a return to senses.

Any couple from, say, west of the Mississippi could figure on shelling out from $2,000 to $2,500 to savor the sweets of victory. Betty and Jerry Anglin set aside $5,000, just in case. A Houston bachelor dropped $700 alone on tickets to official events. A seat at Monday's gala cost $150; a ball ticket last night, $250; a choice seat at the prarade, $75; hotel rooms, forget it.

Arnold Steinberg, a political consultant from Los Angeles, knew his folks best. Said Steinberg: "These people have insatiable appetites to attend functions. You tell them there's an event at 3 p.m. and they say, how much is it? There's some fairly substantial people here."

Substantial, yes, and not a little bit foxy, familiar with quirks of the system. In that spirit, some came up with an all-American way to deal with the high cost of patriotism. They could write it off as a business expense.

Homebuilders, limestone quarry owners, electrical manufacturers and political consultants, all called business meetings in Washington to coincide with the inaugural.

But then, money and cost rather miss the point. Agustin Prado, the Culver City businessman, said, "I really can't afford this kind of thing, but I wanted to be part of history."

So did Pat Fers of New Haven, Conn., and Len Caplan, from Hamden, Conn., GOP precinct workers. "So far," said Fers, halfway through Monday, "I've spent $500. It's the best $500 I've ever spent. . . . I really feel I'm a part of history."

Amen, added Caplan: "It may be a once-in-a-lifetime thing."

Nolan and Jacquie Brunson of Hobbs, N.M., came because they are lifelong Republicans and this was a moment for all Republicans, no matter their station or style. Since Barry Goldwater's 1964 campaign, they have been true-blue conservatives. And Reagan wasn't their first choice in 1980; John Connally of Texas was.

That didn't matter. What mattered was that they wanted "to see the beginnings of a big change in this country."

"Yes, sir, we're conservatives. Conservative enough to think, we can get along with less government, not more government," said Nolan, an independent oilman, on the Capitol steps after Reagan's swearing-in. "The ranchers and farmers and businessmen in our part of the country are tired of the federal government intruding into their affairs."

And then you had another kind of true believer, the Reagan supporter who sees a strong change coming in foreign policy matters. Jose Casanova and Alfredo Marchargo of Miami, Cubans who are now U.S. citizens, put it bluntly.

"We feel Reagan will provide strong leadership in dealing with Fidel Castro's expansionism," said Casanova. Added Marchargo: "In two days, Fidel Castro will be crying. Reagan will do everything for America."

That's the way Jim Reed, a black from suburban Englewood, N.J., saw it too: "You'll see more positive action from Reagan. Jimmy Carter tried to please everyone."

Reed also had a thought about this question of the Reaganites and their style.

"I'm a courier in New York City," he said. "It's an honor for me to even be considered for an invitation. A lot of wealthy people from Englewood are not here and they want to know why.

One more thing about the limousines, style and spirit:

"I think it's extremely awesome to see all the limousines," said Wilborn L. McDougal, a Republican national committeeman from Salt Lake City. "The limousines give you a feeling of pride and accomplishment. It gives you a feeling of enthusiasm for your leaders."