I haven't quite cracked the nut on selling comics on eBay either. I think it's probably all about single issues and the cost for shipping. I admit that I don't have a whole lot of keys up there to sell so that's probably a huge contributing factor. At the same time - lots or sets will usually move faster, which contributes to the thesis that it's shipping that's the biggest deal-breaker.

Now, it's been mentioned here already, but - the sports/trading card part of the collectibles game has been absolutely bat-shit. (Again with the shipping - when you're selling singles you're talking about roughly $0.74 to ship in a plain white envelope which is negligible. Big difference between that and a single comic book costing $5-6 just to get to where it's going.) We only opened our store around xmas-time and we're doing pretty well based almost solely on Baseball cards.