Depends on what your current costs are and what you consider "cheap". I feed mine about a 50/50 mix of pellets and freshwater fish. Getting a high-quality pellet helps me to feel comfortable with the number of nutrients they receive, and even though a good pellet costs around $10 per pound, they seem to eat considerably less compared to raw fish. The other 50% is usually sturgeon, crappie, or bluegill. Usually we go fishing, catch quite a few and freeze the fillets for later use. If catching your own fish is not an option, usually most places have seafood markets where you can buy bulk fish and freeze them yourself. Frozen fish is definitely your best option, but places like walmart and other big name stores probably won't sell at the prices and quantity you need.