For the purposes of the average retro video game fan, at least the ones I know, this system simply cannot work. I've never met someone who buys 20 year old games and doesn't care about condition, or is interested in buying a game for a set price but doesn't care to even know if that game comes with a case or not until it arrives at their place. I've never met that guy.
I'm having a hard time trying to think of any place that just sells "used game" or "used anything" where you can't see the thing first, there is no description of that specific copy, and there is no way to talk to anyone about it.
dkoldies, rock30games, lukiegames, gamestop. they all do it that way, i believe they all have no questions asked return policies for a specific set of time if you are not satisfied. not sure why anyone would buy at any of these places as the pricing is usually higher than ebay anyway.