I smells like some of that brown toilet filler to me. 20 bid retractions ain't rite! With only 17 total feedbacks in his short eBay career, it looks like he retracts more often than he wins. I think you have a clear case to complain to eBay and get him suspended.

Here's why he retracted his bid.
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=499353509

What's not clear from the history on your chip, he was second high bidder for some time, with a bid of $50. Then he came in and bid more which probably put him on top. We can't tell how much that was. Then he apparently decided to abandon your auction and take his chances on another. To me this clearly violates eBay's retraction rules, which state:

It's OK to retract a bid if...

You accidentally enter a wrong bid amount. For instance, you bid $99.50 instead of $9.95.

The item description of something you're bidding on has changed - a lot!

You cannot authenticate the seller's identity.

It's NOT OK to retract a bid if...

You change your mind about the item.

You decide you can't really afford it.

You bid a little higher than you wanted.

Unfortunately, you can't leave negative feedback for a person retracting. He's apparently decided it's a valid bidding strategy. And the items he's retracted from don't show up in his biddding history. I think it's clear he retracts whenever he feels like it. You need to convince eBay to explain the rules to him a little better.