Do I have to return the deposit to an Ebay buyer that didn''t buy my car.

My auction did not specifically say "Non-refundable" but I did use Ebay''s function to require a $500 deposit within 48 hours. The buyer paid it, but did not return any of my contacts until after I filed a complaint with Ebay 11 days later. 32 days after end of auction he has still not paid the balance. There was plenty of communication. I gave him a deadline in which his response was to deduct the Ebay fees and send him his deposit back. I don''t so much care about the money, just care that a deadbeat doesn''t win. Im learning that some people consider the definition of a deposit: "method used in having someone else store your money free of charge that they have to return to you at any time and for any reason or none at all in exchange for them being contracturally restricted from selling something to anyone but you for as long as you can get away with it. Or a way of stopping someone else from selling something if you feel like it with no risk to yourself."