Once upon a time, the sample sale had all the cachet of the 99-cent store, as bargain-hungry shoppers slinked around searching for rock-bottom prices on designer duds.

To get to the bargains, customers literally had to descend into the basement.

Leave it to Los Angeles to add a dash of glitz, transforming the humble sample sale into an exclusive, invitation-only event. Sample sales are so popular that public relations firms now stage them to lure celebrities and generate buzz for their core clients. At some events, it’s hard to tell whether people are there for the prices, the party atmosphere or the networking opportunities.

One early participant was Planet Lulu, which was started in 1998, almost as a lark, by Noah Soltes, a 41-year-old former cosmetics manufacturer. “I didn’t know what I was doing,” says Soltes. “I didn’t have any retail experience.” But the success of his first sample sale in a downtown Los Angeles loft persuaded him to make it his full-time business.

Hundreds of women queued up in the cold for the chance to buy designer names such as Oligo Tissew and Rebecca Taylor at 40 percent to 80 percent off retail, Soltes said. When the communal dressing rooms filled up, women started trying on clothes in the aisles. “People were getting naked in front of me,” Soltes says. “Designer jeans were spinning on ceiling fans.”

Soltes gave away licorice, candy and drinks to keep the mood jovial. But what kept the women coming back were his cheeky e-mail invitations.

A typical missive gushes that “You are so invited,” before launching into a stream-of-consciousness confession from Soltes’ childhood, usually detailing his unrequited love for a neighborhood girl.

But whimsical e-mails don’t produce profits by themselves. “Noah has a good eye,” says Stevie Wilson, a fashion editor at Orange Coast Magazine and a frequent Lulu shopper. “Lulu is successful because they really know their merchandise and they really know their customers.”

Lulu grosses more than $1 million a year, according to Soltes, and it soon inspired imitators. Companies such as Sassy City Chicks and L.A. Fashion Co-Op added perks including beverage sponsors and a DJ spinning tunes to create the feeling of “a girls’ day out,” said Kimberly Tominaga, founder of Fashion Co-Op. “It’s like a shopper’s Disneyland,” she says. “Girls come in groups of five and spend the whole day here.”

Sample sales are held at various places, such as Bergamot Station in Santa Monica, Smashbox Studios, House of Blues, and the Hollywood Palladium. Some are held in hotels so they can serve alcohol.

The items sold at sample sales traditionally were manufacturers’ samples of the upcoming season’s items. Once the stores ordered their goods, the samples were sold. However, the merchandise sold at today’s sample sales also includes some clearance items, typically of higher-end stuff. What’s more, Soltes sometimes contracts to have a manufacturer produce an extra run of items that clients have already ordered and sells them to his customers at a discount to retail prices.

The discounts can be fairly steep. Wilson says she paid $80 for a cashmere sweater that retails for $200. “People just about choke when they find out how much I paid for it,” she said. She also bought a $300 denim jacket for $60.

The new breed of sample sale even has the chutzpah to charge entrance fees, ranging from $3 to $25 for Sassy City Chicks’ VIP ticket, which gets you early admission, a goody bag and free mini-massages or eyebrow waxing.

But the Neiman-Marcus of the sector may be Billion Dollar Babes, whose quarterly sales draw some 3,000 women looking for discounts on luxe designers such as Ted Baker and Jenny Packham. Shelli-Anne Couch founded Billion Dollar Babes with her partner Kate Nobelius as a sideline of their public relations firm.

Anyone can get an invitation to the Saturday portion of Billion Dollar Babes’ two-day sales, but the Friday VIP preview is limited to 300 shoppers who pay $100 or $200 for the chance to rub elbows with bargain-hunting celebrities such as Naomi Watts or Jessica Simpson. Couch insists that while the stars give her events some wattage, they don’t get any special treatment. (Well, other than free VIP admission.) “Tori Spelling has as much chance of getting that Vivienne Westwood dress as Betty Budget from the Valley.”

A Billion Dollar Babes sale has the feel of an Oscar party, with sponsors such as Armani and Merecedes Benz, and free beer and wine flowing at the bar. “Women absolutely do buy more after they’ve had a few bevvies,” says the Australian-born Couch.

For now, there still appears to be room for all these companies to thrive. “We have a consumer culture that expects sales to happen every two weeks,” says Rose Apodaca, former West Coast Editor of Women’s Wear Daily. “Everybody wants to feel they’ve been invited to some private event and they’re getting stuff on the cheap. I know better and I still get sucked in.”