For whatever reason I was mulling over how the value of resources could fluctuate based on the number of players who possess that resource. What I came up with was a price track with spaces on it where markers are placed from left to right for each player that has that resource. Above each marker space is a price and again going from left to right the price above each space goes down in value. The active price would be the one above the right-most marker. For example the price track for bamboo goes 10, 8, 6, 4, 2. If there are three players who have bamboo in their hand (of cards?) then there would be three markers going on 10, 8, and 6. At that time the value of bamboo is 6 which would be above the right-most marker. If at any time a player depletes his supply of bamboo then the right-most marker is removed (by that player) and then the price of bamboo becomes 8. This way the fewer players that have a resource the more expensive it is (or more valuable for trade) which simulates actual economics.
Does anyone know if this has been done already?
That's a good point about the player psychology. Lowering the value of a resource may be a good thing though. If you need to buy resources to build a building then if the resources are cheaper then the buildings would be easier to build.