This guy should be banned. Still, I would never post an unwatermarked logo in a contest held by a guy with 56 posts and 0 positive feedback. I truly hope you receive your money.
That sucks. You made a very nice logo, too, mate. He or she made a terrible job of putting it on their site (looks all squashed), but that's not a consolation really. Can you get them to take it down via a DMCA request? Or have their home page removed from Google search results due to DMCA infringement? After all, it's your work, your copyright and they have not paid to use it. EDIT: Funnily enough, looks like he has had one in the past: http://forums.digitalpoint.com/showthread.php?t=2491820&p=18019972#post18019972 EDIT2: No idea for what reason s/he/it got banned, but it has happened. What a shame.