I had 15 heavy breed hens, 3 roos, 2 geese and 4 ducks. (so 24 birds) I was spending about 35$ a month before my last broiler chicken died. (we had a broiler hen who lived until she was nine months long story) Turns out she was eating more than 1/4 of the feed by herself, even with her on a diet. My birds also free range weather permitting, and also raid my compost pile, and get kitchen scraps.
I mix my own feed, so I paid
~21$ for oats, and barley per month at the co-op (100lbs each)
~5$ for 50lbs of organic corn from farmer down the road per month.
~5$ for conventional roasted soy from farmer (non GMO) (50lbs lasts 3 months)
~3$ for sunflowers (50lbs lasts three months).
~1$ for osyter shell and grit
These are winter feed costs, before the broiler hen died. Now it is about 20$ per month. I also save a lot on feed during summer months.
As for Eggs.......... we are getting 2 daily (grumble grumble free-loaders grumble) a bunch of the birds went into a molt as the weather got really cold, before that we were avereging 8 eggs a day. In the spring I expect to be able to sell 4 dozen eggs a week. Not sure how much the price of free ranged eggs is around here, since this spring will be my first year selling any, but they should at least cover thier food and bedding costs If I can sell them for $2.50.
As for saving on bedding costs, I found it is cheaper to buy small square bales of hay, from local farmers, plus I dried out the tall grass that my niehbor only mowed once and saved that for bedding. I have also used our own lawn clipings, and leaves. So my bedding costs are about 5$ per month for the birds and the rabbits we have.
I also pay about 10$ a month to have a light on a timer and a non frezzing waterer run in the coop this winter.
