I usually just type "premium costumes" or something like that into Yahoo, and before long you can find a ton of costumes in the $350-$1000 range, if that's what you're looking for. There are a couple I've been wanting, but paying that much for something you'll probably only wear for a few hours is insane. You're right, most costumes under $100 are cheap crap.
The best costumes I have ever seen were homemade.
The best costumes I have ever seen were homemade.