I have done the calculation on feed costs if you are feeding your birds certified organic feed. Based on WHOLESALE feed costs of $15/50 lb bag, that comes out to 30 cents/lb. According to the label on the bag, each hen should eat 1/4lb per day. In a week that would come out to 1.75lbs or about 50 cents per week per hen.
(This assumes that there is no wastage. I find that the chickens do not like the smaller crumbles and usually leave them but they are figured in the weight of the bag).
Multiplied by 52 weeks per year you are at approximately $26 per hen per year in feed costs. (Free ranging is estimated to reduce feed costs by 20 to 25%).
Assuming a dual purpose heritage type breed lays about 240 eggs per year or ten dozen eggs, you would need to charge $2.60 per doz just to break even. That does not include costs for the cartons, electricity for lights and heaters for waterers in Winter, costs of a coop, land costs devoted to the chickens, and any transportation costs or market costs if you sell at a market or do deliveries. (Remember, a passenger car is considered to cost 50 cents per mile as per IRS regulations in gas and wear. Trucks would be more).
I would say you would need to charge a minimum of $3.50 per doz if you are doing certified organic. Prices here for such eggs start at that and range to $5 at some markets and in the health food stores. This means you would have to sell to suburban and urban markets, not in the countryside, either by way of farmers markets, CSA deliveries or the like. I have an egg CSA where prices start at $3 and go to $4 depending on how many weeks you buy. I am sold out with a waiting list as long as the list of the members. I am on the edge of the suburbs so all pick ups are at the farm. No deliveries or farmers markets.
The egg people at our local farmers market who sell for these types of prices sell out in the first hour. They are starting to take pre payments the week before so customers can be guaranteed their eggs.
Non organic feed is about half of this cost. The non organic feed, however, will consist of genetically modified corn and soy which has been sprayed with pesticides and herbicides and grown on chemical fertilizers. In the case of the Bt GM feed it will have Bt directly inside all of the cells of the plant, instead of just sprayed on the outside. Bt is allowed for certified organic if it is sprayed but not if it is incorporated into the plant tissues such as it is in GM produce. It's your choice.