I found
this thread off-forum to be a good starting point.
On costs, many states permit a small farm to butcher and sell a limited number of poultry per year without getting into any of the regulation. In my own state that number is 1,000 chickens or 100 of any other poultry breed.
IMHO, buying feed in any format other than by the ton is mostly for homesteaders growing their own food for health or hobby reasons [or in a whole-system wherein the animals are workers as well as a product.]