I've had some real problems lately on having an auction run, and in the end, the buyer flaking and not paying.
Ebay is 'supposed' to be good about compensating back for this type of thing if you go through their process and file a claim, but I had one occasion where I never got a refund.
The non paying bidders have even had reputable feedback - this seems to be a growing problem, from my experience at least.

