The bait stores in the Boston area all seem to be strictly worms, I don't know if it's legal or what. If any fellow M*******s know of a baitshop that does, let me know.
The LFS crayfish are pretty pricey ($5.99ea): they're priced as pets not food.
I definitely hear the logic of the argument that breeding feeders is inefficient. When it comes livebearers, I agree. But some crayfish species have ~300 young at a go. I have time. They are low maintenace (to keep, again I know very little about breeding). Weighed against $5.99ea, I feel it's an option worth looking into.