I actually have some math for meat turkeys I did. This isn't for breeders but for getting meat birds in 4 months.
I figured out that it takes about 4 lbs of feed to get 1 lb of live bird. I don't know if that's right or not but it's a safe guess. Your bird will dress out at 80-87% according to some websites I found.
So if you want/will get a 15 lb bird it will dress out about 12lbs of meat (including gibs I think).
4 x lbs of live bird = lbs feed needed. (15lb bird will run you 60lbs of feed if this is right - if it takes 16 weeks maybe 18, not if it takes you 5-6 months to get to that weight, it could be more like 6:1 or 10:1 in some of the slower/heritage breeds, you should be ok I think around 5:1 or 6:1 with palms.)
that number x price of feed (per lb) x .8(dress weight) is how much it will cost per lb of meat you get.
Good luck!!!