I feel your pain, when you have lots of watchers and more than one bidder, it really hurts when the winner is silent. It becomes too late to offer a second chance to the runner up, they are no longer interested, of course you don't know who all those watchers were, and you have a dead-beat buyer.
Beginning next month (I believe) you can specify payment due in as little as four days on auction listings. If I remember correctly once you have that in your auction and payment is not made within the four days, Ebay takes over and you don't have to wait for response from buyer, you can relist immediately.
If you have an Ebay store you almost have to run an auction to get the traffic to your store, so at least the agony of a non-paying bidder is shortened come September.