The bidding sites require you to buy points or bids or whatever the individual site costs. You use a bid/point every time you make a bid for an item so you're paying just to bid, technically. You'll wind up bidding in increases of a penny or a nickel, depending on the site so, when the auction ends, the prices tend to be lower than on Ebay for example. If you win, you not only pay the price for all your bids but you've won the privilege of paying the auction price for the item, too.