Was just discussing this Saturday on my radio show, The Hobby. I agree with the overall point - that walking into a show, setting up and listing low is not enough. My friend Bob and I were expecting a bit of action merely from having nice graded stuff available at eBay prices or lower. Didn't happen.
Doesn't appear that Saturday's episode is up for some reason but here is a link to others, if you're inclined.
http://audio.wgr550.com/the-hobby.htm
Mike