Bloomberg: EBay is introducing ads that merchants will pay for only if they lead to actual sales, seeking new revenue opportunities for the online marketplace before a planned split from the PayPal payments division. The service, called Promoted Listings, will let EBay sellers specify what percent of a product’s sale price they’re willing pay in order to run an ad. The higher the percentage, the more prominent the ad will be, although EBay will also consider a product’s popularity and the seller’s reputation.