CAMP HILL, PA. -- The doors are due to open at 10 a.m. The crowd began to gather at 9.

By the time exhibit organizer Larry Stimson calls out "five minutes!" the air is fraught with anticipation.

"Better get out of the way," Stimson warns. "This is like the Indianapolis 500."

The doors open -- and the 49th annual meeting of the National Button Society is on.

For more than 600 enthusiasts from 35 states and six countries, the week-long orgy of buttonmania began Monday with receptions and lectures at the Penn-Harris Inn and Convention Center. "There is a beginning, but there is no end," says Lucille Weingarten, president of the society and a collector for more than 30 years. "Once a button collector, always a button collector."

"We rush in to see each other's stuff, and tear each other's eyes out if someone did better," chuckles one.

With 1,603 entries of 20 clothing buttons each in 147 classifications, the competition this year was fierce. On Thursday the showroom finally opens: The results of the judging are in, and the dealers' stalls are set up. It's time to buy.

Button hounds of all shapes, sizes and ages pour in, navigating politely but firmly to their destinations, armed with magnifying glasses, button measures and the huge "The Big Book of Buttons," the button collector's bible.

Some go straight to the judged display. Others park themselves on chairs in front of the horseshoe-shaped stalls. What they are looking for: shapes ("since most buttons are round, a square is a real find," says Weingarten), antiques ("before 1918, that's what makes a button old," says collector Carol Ann Stimson), museum quality (Pablo Picasso and Salvador Dali are a few of the better known artists who created buttons -- "they'd be pretty hard to find," says dealer Rex Lay) and something by the late clothing designer Elsa Schiaparelli.

"I'd kill for one of hers," says Lay, an Australian who lives in Holland and writes cabaret revues for the fringe theater in Europe -- and who sells buttons to pay the rent. "Only one I ever saw was in the Victoria and Albert Museum {in London}. It was a trapeze artist, swinging out perpendicular from the bar, which was stitched onto the jacket. Beautiful -- a real work of art."

But beauty isn't everything. The key to a truly great button collection is variety of materials. "Diversity, diversity, diversity," Weingarten explains. Her own tray, which won first prize in the Oriental Pictorial category, boasted buttons of ivory, ivoroid, ceramic, silver, even the lowly celluloid.

"Holy hell, how many more materials can I have?" exclaimed a competitor in a cream knit dress and a bit of a snit, comparing her tray with that of the first-prize winner in the Human Heads category.

For those on a budget, buttons are a best bet. In the "poke boxes" situated everywhere, "you can still get gems for pennies," says Weingarten. But others are pricier, and those little bags of buttons fill up fast.

Customer: "How much do you have me at now?"

Dealer, checking his paper bag jottings: "Looks like $1,700."

Customer: "Oh good, I'm still fine."

A really rare piece can go into the "three and four figures," one collector whispers conspiratorially.

"We used to collect antiques, but these are less bulky -- and quite lucrative, we're finding," says dealer Betty Ashby, a retired psychiatric social worker. She traveled with her husband Brian, a retired educational psychologist, from their home in the Borders of Scotland just to attend this convention. It's their first trip to the United States.

"We did have a bit of trouble on the way here," she says. Their button case set off some beepers at customs. "We weren't searched, though. We just told them it was buttons and they passed us through."

Most sought after are miniatures, the delicate portraits on ivory and silk-covered buttons that were la mode in 18th-century France. Louis XIV and his fashion-conscious courtiers would commission an artist to design a button and an artisan to make it. "These were men, you know. We were proud peacocks in those days," says Denver Elliot, exhibition coordinator and collector from Illinois, raising an eyebrow. "But of course the French Revolution put a stop to all that."

Men now buy buttons, but not "fop" buttons -- as the fancier ones are called -- but rather military buttons. "Most of the men are into those," says Carol Ann Stimson of Indiana, sister-in-law of exhibit coordinator Larry, a man with absolutely no interest in buttons but with "a mother, a sister and a wife who love them."

Jeffrey Kohn, a physician from Pennsylvania, hopes to retire early and just trade buttons. He put himself through med school that way. He's also intrigued with political tokens -- such as the plain gold buttons etched on the back with a discreet "Jackson for President."

"Very different from today's tacky celluloid campaign buttons," Kohn says.

Except for some of their buttons, the society is anything but antique. With an eye toward the future, it's planning a membership drive. "We want to attract younger members," says Robert Folson, parliamentarian of the Vermont Button Club.

Jessie Pratt, who sells "nice buttons for ladies' clothes" in her shop in Bath, England, does a brisk business in jeweled buttons and custom-designed "realistics" (buttons in the shape of rabbits, say, or Princess Di) among the younger set. "Americans are a little different, though," she cautions. "They mostly like to collect because the research is so much fun -- they have to know every minute detail of their subject. We English aren't quite so enthusiastic."

She pauses thoughtfully, gazing at a tray of silver buttons. "I think it might have something to do with being isolated in the colonies all those years.