Expanding on a plan to sell cable TV ads, eBay began auctioning spots on 2,300 US radio stations Wednesday, according to CNN.

eBay will partner with two-year-old Bid4Spots to power its new eBay Media Marketplace for Radio. All major radio operators are participating, including Clear Channel, the largest. The plan will cover 300 of the largest radio markets.

Some 90 percent of the inventory consists of spots that air during lucrative "drive time" hours.

Though radio is being embraced, eBay's Media Marketplace for Cable faces continued resistance from sellers. Only the Oxygen Network has jumped aboard. The Cable TV Ad Bureau pulled out, calling the system "unworkable."