I have two non-paying bidders out of three auctions. One says he doesn't have any money (that doesn't stop anyone else from buying anything) and the other has gone incommunicado. The first has feedback of over 100 and the second has feedback in the 200s. It surprises me, since I usually only see NPB activity going on with sub-25 users. eBay doesn't offer much recourse for non-paying bidders. Sure, you can leave negative feedback and fill out a NPB form (which is akin to a slap on the wrist), but in the end, the item did not sell, and people who would have bought were blocked by people who weren't serious about buying.