(Copied from BukkitDev)
We recently implemented player shops with the Chest shops feature, and one of the first questions the player had was, "what is the point of trade chest as it buys and sells at the same price?"

I'd like to suggest enhancing the trade sign for chest shops so that you could define two prices, and for buying and one for selling. For example the first line of the sign could be entered as 1$/2$ where the first would be the price the chest buys the stuff and second the price the chest sells the items. That way the shopkeeper could set up a simple trade chest that would allow him to make a profit with a Trade chest.

This is complete.