When you think of the online auction site eBay, you probably don’t think of the fashion runway or cutting-edge designers.

But maybe you should start.

In an effort to delve into high-end fashion, the company once known mainly for quirky collectibles has begun partnering with up-and-coming designers and putting items straight off the runway up for auction.

“This is definitely a way to bring the excitement of the runway to a wider number of people,” said eBay style director, Constance White.

Recently, the site — which has 105 million users — teamed up with designer Diane von Furstenberg (search) to offer a few runway pieces. And eBay has also given exposure to lesser-known, but still hot designers like Proenza Schouler and Narciso Rodriguez, whose shows the online auction house sponsored.

Rodriguez has dressed stars like Cameron Diaz (search), Hilary Swank, Salma Hayek and Katie Holmes. Pieces by Proenza Schouler, which is actually two 25-year-old designers named Lazaro Hernandez and Jack McCollough, are frequently featured in Vogue.

“It’s a nice avenue for up-and-coming designers to get a little more exposure,” said fashion expert Elycia Rubin, author of the forthcoming book “Frumpy to Foxy in 15 Minutes Flat.” “It’s really hard when you’re little and struggling to get into a big shop. EBay has such a wide reach.”

A spokeswoman for von Furstenberg said the designer decided to do an online auction to tap into parts of the country that might not be as familiar with her clothing lines as urban fashionistas are.

“As much as we do have recognition, there are always those places you don’t reach, like Middle America,” said Jennifer Talbott. “We’re not a household name there. The exposure is good for us.”

EBay’s journey from garage sale odds-and-ends to designer fashion began in the last three years, as items from big-name designers began appearing for sale on the site. It also recently launched an online fashion guide called “Personal Style.”

The category has grown to so much that it represents $2.2 billion in revenue for the auction company and is one of its top eight categories, according to White. In fact, two of the most searched terms on eBay are "Louis Vuitton" and "Gucci."

“EBay’s fashion business has caught on fire,” White said.

And while it started as a place to go primarily for vintage pieces, about 55 percent of the clothing on eBay is new or “gently worn,” she said — which is where the runway merchandise comes in.

“They’ve already established themselves in the category,” Rubin said. "In order to expand their reach, this is the next progression for them.”

In the von Furstenberg auction, a gold evening gown from the spring 2004 fashion show was sold for $400, as well as two hard-to-come-by tickets for the fall 2005 show that went for a total of $510. A dip-dyed white chiffon gown made for Uma Thurman (search), but never worn by the star, had a final bid of $400.

“We tried to create it so these things were not easily accessible in any other way for the consumer,” Talbott said.

In the Narciso Rodriguez auction last year — the first time eBay tested its runway strategy — clothing from his fall collection and a couple of looks from the runway were for sale, including a sequined dress and a two-piece coral skirt suit.

“Those clothes are not in stores for another six months,” White said. “It served our forward fashion customer and helped us wave the flag and say, 'We’re really a source for fashion shopping now.'”

And now that the treasure trove includes one-of-a-kind runway pieces, eBay is bringing what was once only for the fashion elite to the masses.

“There’s definitely a trend and people are ready for it,” White said. “That’s what ‘Sex and the City’ did.”