I'd honestly skip eBay altogether unless you find an authorized dealer, because you don't get any warranty if you don't purchase from an authorized dealer, and you lose the 'you break it, we replace it (once)' and the lifetime defect warranty that Monster gives you.
But, it's your decision. They don't look suspicious, but there's no concrete proof they aren't fake. You're probably safe given the seller's ratings, but take everything with a grain of salt.
Edited by ethan961 - 11/28/10 at 6:23pm