Was feed Oxbow, but I may be adopting two more that haven't been taken very good care of so since I will have 5 I was looking for a little better cost option.
I use MannaPro, and get it for only about $16 for a 50lb bag from tractor supply. Although if you don't have a place to store that much food, you might want to buy smaller quantities... but the larger bulk bag is definitely cheaper.