Does anyone know if there are any good Sci-Fi and Fantasy trading sites? Similar to Amibay, but for trading Sci-Fi and fantasy items like vintage Star Wars figures, Comics, books, dice RPGs etc...

I'm thinking of creating one and just wanted to know if any already exist. I did a bit of Googling, but didn't find anything any good. Most sites I've looked at go to dead links or strange pages that don't actually contain anything. A few go to Sci-Fi forums with a selling section, but not much activity. So this seems to be something that is needed for Sci-Fi and Fantasy fans to use as a good alternative to ebay.

Good idea?

I'm currently looking at options on how to set this up. Either as a forum based trading site in a similar way to Amibay, or as a listings/classifieds buy it now auction style site like gumtree.

What is everyone else's thoughts on this idea? Good or bad? Worth while?