I'm hesitant to answer because it'll just make me cry. Depending on breeding projects, my monthly fish food bill is around $300. When I had all the tanks running, I was buying food by the pallet and freezer-load. The monthly feed bill was around $750-$1,000. That's not counting the tanks I was breeding and raising feeder fish and invert species in. I also did alot of fishing to supplement the food stores. If I caught 10 crappies I kept 2 for myself and cut up the other 8 for the tanks. Add to the bill the costs of running a hatchery fridge and large chest freezer.
I remember when I was first struck by the fact while I was eating a PB&J sandwich while feeding 4 pounds of large shrimp to the tanks that I realized where I fit in the pecking order in my own hatchery.