My 4 hens are free range and eat almost no commercial feed, maybe 1 lb. a week. They find their own.
It is very difficult to make money raising chickens on the small scale that most BYC readers use. There are, however, some people on here who survive on raising chickens as a business.
You need to do some searches in the "Feeding and watering your flock" section. Many here do keep records, though many others do not. You will find some actual facts and figures there.
Be aware that there are basically 3 different kinds of chickens, in terms of the economics. There are meaties, or Cornish Cross (Cornish X,) there are standard breeds (which includes "heavy" breeds,) and there are bantams, or smaller chickens. There will be 3 different experiences with each of the 3 groups. Since you were asked to design a coop, I assume the assignment has to do with a small backyard flock. In a backyard setting, none of the 3 is ordinarily profitable. The expense is probably most often varied by things like selling eggs, selling hatching eggs, selling chicks, and selling dressed birds. These are often complicated by local laws.
Just trying to give you a little background from which to launch your research. Good luck.
