Although it might be having trouble attracting cable TV networks to its online ad sales system, eBay hopes to have better luck with radio stations. The online auctioneer is partnering with radio-advertising start-up Bid4Spots on getting more than 2,300 radio stations to sell airtime to advertisers through eBay’s Online Media Exchange, WSJ reports. However, advertisers on the OME, which include Home Depot, Intel and Microsoft, among others, haven’t endorsed eBay’s radio exchange. But eBay counters that the radio effort is a separate initiative that’s meant for a different type of advertiser. Also, the initiative is meant to counter Google’s moves to offer online advertising opportunities to radio stations, especially since the internet search giant introduced its Checkout online shopping service last year, which rivals eBay’s PayPal.