Where to buy decent costumes for conventions?

I'm aware that most people make their own, and I was planning on doing so but I wanted to know if there's a website (other than ebay of course) where I can find movie replica props of superhero costumes (preferably inexpensive) so I don't have to make EVERYTHING. For example: when I was a kid, I went into a random costume store (I don't remember where it was, I was traveling) and I found a replica of the Robin belt Chris O'Donnell wore in Batman Forever, and I haven't found anything online.

Posted in batman forever