If you've just got a few snakes, I think you're better off just buying your mice. I never started breeding feeders until we got enough snakes so that we were spending $20+ every week to feed them. And that's probably just because my mom had chickens and rabbits and dogs, so we wouldn't have to buy any more food just for the rats.
....now she's going to start breeding some rabbits for me
....now she's going to start breeding some rabbits for me
