Don't fudge on your costs. Put it all down. If you manage your birds well and have a dressing plant nearby that will process for a reasonable cost, or if you are willing to do this skillfully yourselves, you will have to put up the money for the first batch of birds, then the capital they generate should cover the expenses for the next batch and pay some profit. Lots of people who contribute to the Coop site would be happy to help you as you plan for and carry out your project. Good luck to you.
Eggs are less than a dollar a dozen and chicken meat is also very inexpensive.
Building our coop was expensive. But it's a really nice shed. I don't raise my chickens for meat, but keep in mind the time spent plucking and preparing them. I've never done it, but I hear it takes some time. That would also make it more cost-effective to buy the meat in the stores.