If you live in North Texas and absolutely don't want to do it yourself, http://hayesfarmtexas.com/ does it for $1 a bird, but you have to bring a cooler and throw the processed birds into the cooler yourself (I think they might bag the bird for $0.50 more per bird).
It is clean and sanitary, but somewhat crude surroundings.
From what I've been able to find, the nearest USDA processor to TN is in southern KY. From the directions given, it's just off I-65 somewhere (105 miles north of Franklin is the only thing I committed to memory). Since I want to sell to the public, I'm gonna have to make that trip and add it to the final selling price (my truck only gets 12-13 mpg...and it's diesel).
In Washington, I have two choices. I can get a permit to slaughter them myself on the farm, then sell them from our farm within 48 hours of the processing. The second option is if I go to a state inspected procesor, I can then sell them off premises like at the farmer's market. The catch is we cannot process the birds at all, which means we cannot even freeze them. Since it's about a 90 minute drive to the nearest processor, I get as many people as I can to pre-order then pick the birds up at our farm. The balance I freeze them sell at the Farmer's Market the next Friday (and typically, chickens sell out within the first couple hours, even if I have 30 left to sell). My food safety inspector (the guy who inspects our farm) is OK with what we're doing, taking them out of state.
In Oregon it is my understanding that you must use a USDA processor for poultry to sell them off your premises (which really sucks). This may be wrong, but everyone I've talked to in Oregon has to skirt this law because it's entirely impractical.
The one I use most commonly is Harrington's in Boring, OR. The two nearest to me in Washington only do poultry 2 or 3 days per month, so it's an immense pain in the ass to work with them. Harrington's pretty much kills 5-6 days per week. You just have to be very careful to get your birds chilled to the right temperature for the ride home.
[edit] Also I forgot one thing. If you are doing other meat animals, Buxton Meats in Sandy, OR is just about 10 minutes past Boring. It is a small USDA inspected facility wihch means you can sell the meat retail once they have cut & wrapped it for you. It bears all the appropriate USDA approved labeling and everything. The one butcher is from Edinburgh, and trained in Scotland. He does a utterlay spectacular job on the lamb, beef and pig we've taken into him.
I just wanted to remind everyone that check the rules in your state. Many states do not require USDA inspection for poultry and rabbits; but require only state inspected facilities. Other states do require USDA inspection. Don't go the extra mile for the USDA stamp if you don't need it and it will save you money.
I never look at price per pound. I'm doing it for enjoyment.
Worth in NO. I also fish and if I figured out what I pay for a pound of fish it would make me sick. Some folks smoke some drink and others are going out to dinner and movies.
Not saying I don't indulge in some activities but raising chickens is peaceful and enjoying. John