If you want something to trade in the new system, build up all the stores of precious metals, food and other stuff if you like. Food will spoil ... even many dry goods (though not all) but if you build up a nice stockpile of weapons and ammo, those will ALWAYS have an extreme value to people. You can defend your products at the same time you are selling them. Mind you, a store of dry goods may not be a bad idea either.