I'm finding it isn't all that difficult, at least here in Oklahoma. I'd look up poultry exemption laws in your state. The USDA exemption from inspection is 20,000 birds per calendar year, but what states allow varies from state to state. Oklahoma it is 1,000.
A decent processing setup is around $2,500, to just get you by, unless you build your own plucker and scalder. I wouldn't try to do large amounts without a setup. Unless you pay yourself a salary or your time would make more doing something else, your labor is free. Without the advantage of growing my own grains, purchasing and raising the birds costs me about $5 each. I am selling them for around $15 and up, and raising them on pasture to add to their nutrition and joy of life. That's potentially $10,000 a year profit. Almost pays the mortgage. I market them at the local farmers market, taking pre orders there for on-farm pickup and payment. If I buy and license a refrigeration unit, I can sell directly at the market.
I would second the suggestion to check out the Salatin book. You can get it at your local library. If they don't have it, ask them to interlibrary loan it for you.
If I think of anything more I will let you know. Meanwhile, I say go for it and have fun.