Everything. That way you can buy what ever you want. I have a chest full of fishing worms and a chest full of gold coins plus 3 or 4 chests containing jewels and nothing to spend them on. He could sell arrows, ore, seeds, cores, foods, (maybe spices that increase the health and stamina value of foods they are used in) and just about any thing else. It would be cool if he bought surplus goods like troll hides. There's only so much coal I need from the obliterator.