There is nothing more upsetting than carefully constructing an ad, listing it on ebay, waiting days only to have a nonpaying winner bid on your item. There is a few ways you can avoid this issue BEFORE it begins. The most important thing to do is preventenence. When you are sitting there wondering what to write about your item description make the first line in all of your auctions state something like this "Please READ ENTIRE AUCTION for instructions and payment details"  i have noticed that quite a few of my unpaid items are NOT from people with negative feedback on the contrary they are from people with either a 0 or 100 percent feedback that FAILED TO READ ALL OF THE DETAILS about the auction. the item description section is not only to describe your item its to tell people HOW you want paid ,IF an item SHIPS OR NOT, if you sell to international buyers , and how many days the buyer has to pay. some of my non paid items are because the buyer wants the item but fails to read the item description that maybe its too big to ship therefore in the first paragraph i put in large letters ITEM TOO LARGE to SHIP , LOCAL PICKUP OR BUYER ARRANGES OWN SHIPPING.  the bigger the letters the better it is for the buyer that just 'SKIMS' over the auction ad.

one other way you can avoid a nonpaying bidder is to do some research on the people that are bidding on your auction.. if they have a history of negative feedback either delete them as a bidder and block them or set up some special terms ahead of time. what i mean by this is i was selling a corvette on ebay motors and as much as i hate to deter a potential bidder i wasnt happy with the highest bidders prior feedback. i kicked him off as a bidder and blocked him, i got an email from him stating that he really wanted to buy my car. so i told him that if i didnt get a winner bidder he could get it for my buy it now price and that he had to have half down via paypal or other secured funds  for a NONREFUNDABLE deposit. At the end of my auction i didnt have any winning bidders and again this buyer contact me. I actually sold my car to him , and even with all of his prior negative feedback i had a very pleasent transaction with him. I dont recommend this to everyone , but if the buyer is serious about your item,and they have alot of negative feedback; see if you can work out some sort of deal way before the auction ends so that you dont end up with being the victim of a nonpaying winner. OPEN COMMUNICATION with potential bidders/buyers is KEY before during and after the auction to make it as successful as can be.