Well ours get 300g of rolled barley in
water in the morning and 250g of wheat in water in the evening. Plus any bread scraps that they can fight the
chickens for. And they forage over 2 acres - LOADS of slugs and snails. It's rare that we have snow covered ground so they can always forage. Not much point me giving you costs as they'd be irrelevant (you're in North America??)