It's questionable at times. Item value on p99 is a perception.
Then account for the fake sales and people making alts to jack up prices listed there.
Those kind of people will tell you that you're asking too much, Then turn around and spam wts for 12 hours everyday at twice that price.
I know of one person who doesn't play the game other then to TunnelQuest. Meanwhile he's ruining the game for people who actually play the game.
It's not the auction site(s)'s fault though. They just parse what people auction in EC, which doesn't show how much people actually pay for thing.
http://ahungry.com/eqauctions
http://www.p99auctions.com/