Pure Insanity
Sorceror
Believe it would make more sense to base the % increase/decrease by the count of how many exist in player hands. But then to make it even better, you'd need to come up with a formula of which items are collected to determine it's popularity and base it off a base price with some made up formula. Making a perfect economy isn't easy, if even possible. Pretty much every single nation in all of history has failed so far. =P