When there's a consistent imbalance, I wonder if instead of trading it themselves, they could queue up requests. People who really wanted the cheap rate would wait days or weeks or whatever it took to reach the head of the queue, while others would drop out so it keeps moving.
Great idea. Maybe they could go one step further, and automatically lower prices until someone does buy them out. They could call it something cool... something that reminds you of places where you can buy and sell things... :p