This is just my 2 cents. I agree it's very difficult to make stuff for the zoo because I need the items, but you can buy the hot items from the market when available. This seems to be the only way I can sell the items from the market for more than I buy them for. So it's profitable in coin & leveling to do so. And since I have been able to maintain the dealer at all times, when I don't need ore from him, I buy hot items that will yield the most profit from him to also sell in the zoo. This worked wonderfully until my level 22 zoo vanished in a blink of an eye, sigh.