EBay, the San Francisco-based online auction house, isn't just for stereos and rare collectibles anymore. A recently launched business-to-business marketplace is also moving roughly 550 items a day in the construction category.

Laser levels, heavy equipment like skid loaders and backhoes, and hand tools like pipe threaders, saws, and hammer drills are among the best selling items, says construction category manager Ben Hanna.

Users, mostly small to midsized contractors, are also buying materials, Hanna says, noting that some suppliers are auctioning overstock or items they just can't move in their regions.

Roman Kaniuga, a New York remodeler, has made more than 20 eBay purchases to equip and supply his fledgling one-man company.

"I've actually learned a lot about tools and the types of tools I need from eBay," says Kaniuga, who, until recently, worked as a risk management analyst on Wall Street. "It's a great venue for buying. You can purchase tools for a lot less than you would pay at a retail outlet."

His best deals, Kaniuga says, include a used Clark OBS-18 sander he picked up for under $1,000 and a new Bosch SDS rotary hammer he bought for $350.

Kaniuga says he uses eBay to buy items he may need for only a handful of jobs, like the new Bosch Brute hammer he bought for $1,050, including accessories and shipping. "I was taking apart a concrete floor, and how often am I going to be doing that?" he says, explaining the purchase.

He says he avoids buying some used items, like circular saws, that tend to take a beating during use. But he still uses the site to research and price tools that he expects to buy new.

Kaniuga says he has, on a couple of occasions, hooked up with unscrupulous sellers. But he trusts the site's seller ratings and his own instincts. And he says he's learned a lot from the community of users. "People always want to share their experience or their knowledge about different aspects of a job."