I think it could be a good idea. SF and Fantasy never go out of fashion, and with the current tendancy for reboots, some of the older merchandise can become a sought after commodity.

Initial thoughts for the style of site would be something similar to Amibay, as that seems to be working. Although, as time and requirements change, so could the set-up, if need be.

Just my initial thoughts, it will be good to see what others think.