There are specific auction websites out there that don’t use cash payments for their transactions. You are required first to buy points and then use the points to bid.
The scam occurs at the end of every bid, when 10 or 15 seconds are added on purpose by the administrators. This allows the users to bid again if they are outbid in the last minute, using more points for every single bid. Studies show that people typically spend points more easily than real cash, although the amount might be the same.