The site, which will be called Entertainment Marketplace, is expected to launch early next year and will combine Half.com's used products with Buy.com's CDs, DVDs and videos.
Under the deal, the co-branded marketplace will be promoted from both sites and Half.com will feature Buy.com's new products throughout its site. Buy.com will plug the marketplace in its "Partner Center," an area launched on its site last month.
Financial terms of the deal were not disclosed.
The partnership stands out in the embattled online retail industry, where dot-coms are increasingly hanging "out of business" signs. In the last month, online retailers Eve.com and Mylackey.com closed their doors after mounting pressure for profits and lack of investor interest stilted operations.
Aliso Viejo, Calif.-based Buy.com--which sells a wide range of discounted products including electronics, books and sporting goods--is using online partnerships with other e-tailers to bolster its revenues.
In October, the company aligned itself with several online car companies such as iMotors and CarsDirect.com to create an automotive center on its site--the first area within Buy.com's Partner Center. By driving sales on these sites, Buy.com makes money from commissions, revenue sharing and joint promotions.
Half.com is a fixed-price, person-to-person marketplace for nearly 7 million previously owned products such as books, CDs and games, with all items selling for at least half off the list price.
Online auctioneer eBay bought Half.com in June for an undisclosed sum.
"This alliance opens up a new channel of millions of prospective buyers for both companies," Half.com president Joshua Kopelman said in a statement.
Buy.com, founded in June 1997, has expanded into Canada, the United Kingdom and Australia.