Sure they've gone back and sold items for cheaper than they came out as, Dino is prime example. The big thing is it would make many people unhappy if they reduced the price on the day of release and didn't give people a refund, which they have no way of seeing who would need a refund. Also, the piano isn't meant for every graal player, it was a rare item released for the Christmas presents, and I'm sure they want to keep it rare.