Nice idea, but impractical, as previous posters have pointed out. If you're a seller, perhaps getting rid of something reluctantly, in order to pay the rent, you would understandably want the best price you can get for something.
Of course, if you're a buyer looking out for something, it can be frustrating that the price is always so high.
I will never forget someone posted an advert on Amibench..
"Wanted: Picasso IV graphics card. Will pay £60, in line with what they go for on this board."
I bet he got a load of abusive emails! Basically, someone had sold one the week before for £60. Hardly a market indicator! Imagine going into a restaurant and saying 'I heard that one day, someone got a free lunch, therefore I demand that you give me a free lunch'
