It would bring you down to his level. The problem 
is that he isn't doing anything wrong. It may not 
be very sporting of him, but his interest is in 
money not cels. It's one thing to sell fake cels or 
claim to have a cel that you don't have, but he's 
not doing anything illegal. I can't condone 
purposely screwing up other peoples auctions even 
if they are posting bogus cels. I think warning the 
bidders would be the best thing to do.

I will keep his business practices in mind when I 
see his auctions pop up on eBay. The sad thing is 
that if he has something that I can't live without, 
then I don't see as I'll have any choice.