I buy the large 20-25lb bag of Nutro Complete Care Weight Management Formula and it's about $28.00 or so a bag. The bag lasts me at least a month to a month and a half. I also mix in a little bit of Felidae dry cat food and it cost me about the same but I'm not going to buy any more after I finish this bag.

I also buy a few treats here and there but they last me for a while and then there's litter. So I guess I spend about $40 a month total for everything and about $30 for food. All 4 cats only eat about 3/4 - 1 cup of food a day.