If he's signed up with ebay, he'll have his details on there somewhere (even if it means you have to bid on the item and win it)

Get the contact info and send some legal documents to him.

This is straight up piracy... Only thing I'm worried about is him saying that he didn't make the recording(s) and that he is only selling a cd which he aquired from elsewhere... and many people sell second hand cd's on ebay.

All you lawyers on here, would he get away with it?