The best thing to do is report them as a non-paying bidder through the dispute resolution process, and place them on your blocked buyers list. Sellers can block anyone with strikes against them for this (and most sellers do this).When you go through the resolution process, you are also refunded your fees on the sale.

This is much more effective - I frequently receive missives from non-paying bidders claiming excuse after excuse when they find they have been unable to buy something of mine.(Most claim it's all a misunderstanding, and has been cleared up with eBay. I simply point out that clearly it has not been cleared up with eBay because it's eBays system that is blocking them.)

This is abetter lesson for people who don't pay, because it really hits home when they can't get something they truly want.

If you go to the site map at the bottom of the page, you'll be able to find links to set up your buyer's restricions, blocked bidders list, etc. Put your blocks in place and you'll have less problems with these time wasters.

Good luck in your future sales,

Marina.