Just from what I have seen, but at the shows the prices often seem to be unrealistic, I agree that especially on postwar, the prices being asked are too high, and it looks like the guys don't sell a lot. The last greenberg show I went to, I heard two of the guys with tables talking, and they were complaining about how people didn't want to pay a 'fair' price, both were selling postwar..and while they had some nice stuff, the prices were well above what I have seen stuff sell for, not talking rare items, saw things like 1990's Lionel Engines they had priced probably double what I could get off of here or on fleabay or dealers on the net. I think a lot of the dealers think they are going to get high prices when the market isn't there.
I did see some modern stuff at tempting prices, if my son wasn't in college, could have gotten some good deals on PS2 MTH and the like.