If you have access to a big mulberry tree or a grove of them , silkworms are the cheapest feeders you can have , once you harvest the eggs from maybe 10 -20 moths (each lays about 400 eggs) , the silkworms become FREE and available year round.
The leaves can be blanched and frozen for the offseason too and the eggs kept in the fridge in airtight ziplock bags or glass sample bottle until needed.
Crickets and roaches are free once you start your breeding colonies.