Before everybody was tossed out on the sidewalk, it was, to say the least, a diverse group that amassed inside Norman Weschler's acution gallery at 9th and E streets NW - secretaries, U.S. marshalls, tourists, near Eastern potentates, camera crews from three local TV stations, gawkers, kibitzers, the rich exuding their affluence in dark pinstrips suits and glasses, and the still richer concealing their affluence in windbreakers and deck shoes.

The underlying purpose of th proceedings was to see who could get what, and for how much, from the estate of convicted embezzler William Sibert, but there was a less formal competition to see who could bid in the most eccentric fashion possible, with an ever-so-slight droop of the chin, or scratch of the nose, or tilt of the umbrella.

At its peak, around 2:30 p.m., the crowd numbered about 200. That was good news to Bill Lengacher of the Justice Department, who was happily counting up the day's take - about $155,000 at that point. But the D.C. fire marshall's office saw things differently, and after several warnings ordered the premises evacuated.

"This is a pain in the neck," said Michael Veneziani, as the crowd received on the sidewalk. "I'm an antique dealer. I was here to bid on antiques. I come here every Tuesday," Veneziani said he had never seen such a crowd at an auction before, and added, "Things are going outrageously high."

The items for sale included 10 automobiles (mostly Lincolns and Mercedes), jewelry, furniture and appliances. All had been purchased by Sibert last summer, after the $10,000-a-year clerk for the Department of Transportation had succeeded in writing $857,000 worth of government checks to himself. The checks were officially listed as going for construction of a subway system for the city of Atlanta.

During a two-month spending spree, Sibert spent an average of $12,000 a day before finally being arrested with a party of friends in Las Vegas last August. Sibert is now serving a six-year prison sentence in Kentucky.

The winning bids at yesterday's auction ranged from $22,400 fr a white, custom Lincoln Mark V convertible, down to $7 for a record cabinet. Some of the bidders were car dealers like Corky Rice of Beverly Hills, Calif., who bought a green Mercedes 450 SL for $20,100, and a Lincoln for $15,150. "I came to Washington to buy cars," said Rice.

Other were Washingtonians looking for bargains. Attorney Louis N. Nichols paid $4,900 for a blue Dodge Diplomat. "I bought it for my son," he said. "They need a car."

At the end of a hectic day, Lengacher calculated that his office had recovered more than $450,000 from Sibert's assets, which included about $300,000 in stocks an cash as well as the items auctioned yesterday. Sibert's houseboat, moored at the Fort Washington Marina, and his interest in the Lone Star Beef House on 9th Street, are the only items remaining in the estate, said Lengacher.