Here's a model for a business. Search ebay for things which appear to be going cheap. Make a stupidly high bid for the cheap item to try and win it at a knock down price. If you win at a low price, pay it. If you win at a high price, delete your username and walk away.
I've had this happen to me before. Up until now the buyers had the "decency" to come up with an excuse for their stupidly high bid before retracting it. This time they just deleted the user.
It occurs to me that eBay should probably keep track of the postcodes used by buyers and check for large numbers of accounts being registered/deleted at a particular location. This would seem to be a good use of all this "artificial intelligence" that we are always hearing about