But usually the shill is in cohoots with the seller. The purpose of the shill is to drive up the price by submitting incremental bids to keep the bidding process going. There are some bidders who do not care how much they pay for the items on ebay ... as long as they are the winner. The shill does not pay anything to the seller in the event he/she winds up being the high bidder. The seller simply pays the commission on the sale and the shill submits positive feedback for the seller and the seller does the same for the shill. The shill could even be a spouse of the seller using a fake bidder screen name and different address. With hidden bidder i.d.'s it's difficult if not impossible to detect from the outside looking in.