I bought a bunch of ex breeders from G & G. Snakes liked em. They eat rats now.
It is to bad that there isn't a source of nutritional info for mice and rats of different ages. I've always wondered if a fuzzy rat is equivalant to an adult mouse. The same fat/calcium issues, perhaps.
I don't think it an unreasonable question either. Consider that a snake in the wild will eat whatever it finds, which almost guarantees a varied diet. If you buy 50 ex breeders, that's quite a few weeks of the exact same diet.
As far as the cost of the animal we're feeding... my dog was free. She still deserves a diet that is healthy.