They were aiming for $10,000 at a benefit Saturday night for the capital Children's Museum, and then came the news that there might be an extra $2-million windfall to help them out.

Housing and Urban Development Secretary patricia Roberts Harris announced to the black-tie crowd at Bloomingdale's, White Flint, that she had "found money in the secretary's discretionary fund, and we are trying to persuade the District of Columbia to give it to the Children's Museum."

Harris said she hopes to announce withing two weeks more details on the new museum or "learning laboratory," located temporarily at Lovejoy School, 12th and D Streets NE.

White House Press Secretary Jody Powell took a break from the Mideast summit meetings and drove from Camp David directly to Bloomingdale's where he changed into a tuxedo which Mrs. Powell and brought from home. Nan Powell and Nancy Moore wife of White House Congressional Liaison Frank Moore, were co-chairmen of the benefit. (Both women are former teachers, and the museum, which is getting more and more international attention, is their pet project)

Asked if he were heading back to Camp David after the benefit, Powell repled with a smile, "Indeed not. I haven't seen my wife in 10 days I'm going home.

Gifts presented by the French Embassy to the museum included a doll with a bisque face dressed in cotton lace and a game of colors by artist Vassarely. Soon to come is a farm house made by French schoolchildren.

(After visiting the museum recently, Mrs. Anwar Sadat, wife of the Egyptian president, sent a collection of carved wood and leather camels.)

Saturday night's fashion show was one of the rare occasions museum-quality vintage clothes were shown on the runway. Designs by Paul Poiret, Chanel, Vionnet and Balencriaga were danced out against a backdrop of slides of the period in which they were created.

The collection of vintage clothing came from the Musee du Costume in Paris, whic is run by the French fashion industry.

Guests also had a chance to talk with several Paris ready-to-wear designers including Chichi and Claude Barthelemy. Jean Bousquet of Cacharel and Elie Jacobsen of Dorothee Bis.

There is never a benefit without complaints and saturday night there were guests (who paid $50 each) less than happy that Bloomingdale's chairman Marvin Traub's table was the only one getting champagne at dinner.

And, Jokingly, there was a "complaint" from Bloomingdale's that the guests hadn't eaten enough, so a roast suckling pig was auctioned off to benefit the museum. Ann White Lewin, museum direction, got the bidding up to $300, and the pig was taken home by Conrad Valanos, owner of the Monocle Restaurant.

"Three months ago I said there were 100 things to fall in place before there would be a national Children's Museum, and now it all seems to be hapening." said Nan Powellas about 350 guests headed home after midnight.