As any other seller on Ebay I am deprived of the chance of leaving negative feedback in the case of non-paying bidder.
I would like to suggest a black list of non-paying bidders and can start one myself. I recently had the following non-paying bidders:
heliiis (based in Estonia)
liberamanuel67 (based in France)
den.horka (based in UK)
coins90236 (based in Australia)
If you have other non-paying bidders, please contact me and I will add them to my list.
In my opinion, it is better to do something to help selling community than to do nothing at all.