Ah, but here's a strategy that might work. Assume a 70/30 split between store and publisher. Allow users to trade in a game license for 20% of current price. Assuming this is the same price as it was bought at, the store still makes 10% absolute profit, and given that it's traded in for store credit, not actual money, you can be pretty sure that the rest of the money will go to the store eventually.
EDIT: If you combine this with Steam-style regular deep discounts, you keep customers happy, even the segment who want to play the games, but who can't afford them at full price.