It of course will depend on how large you grow them. Going that last pound from 8-9 can mean a lot of food. Miss your processing date by a week and it will cost you dearly!
Here is my breakdown from last year. I have yet to calculate this year's price based upon the huge spike in feed prices. I process when my largest bird in the pen is 10 lbs. That gives me the largest dressed birds around 6.5 lbs and of course down to about 3.5 lbs.
Bird $1.60 EA (be sure to include shipping)
Food $9.60 EA
Slaughter $7 EA (don't forget to include mileage)
Shelter $1.20 EA
Portable Electric $1.50 EA
Fountains $0.20 EA
Range Feeders $0.65 EA
Lamps $0.12 EA
Bulbs $0.35 EA
Insurance ??? (depends on your total farm revenue for the year, really)
Total: $22 per bird
All fixed costs are amoratized over the first two years assuming I process and sell 50 birds per year. Last year, I did 75 and this year I'll probably 150. So, I was able to bring some of the overhead down by doing fewer birds.
Of course, everything in the Pacific Northwest (PNW) costs double what it does anywhere else. Dending where you are, you may be able to feed for 20% less than that and process for possible 1/3 what I have to pay.
I sold last year at $3.50 per pound with the average bird size around 6 lbs. So, the first two years is establishing customers and paying for your coops, electric netting, etc. Of course, you can take a few birds for yourself,t hen essentially your customers are paying you to eat your own delicious chicken. That's nice!