This is quite a long response(sorry), but this topic brought a lot of things to my mind:
If your birds are free ranging, they eat a lot of greens, but I think people would be surprised at just how many insects chickens are able to find. I wouldn’t be too concerned about protein...
We had an idea to reduce feed costs and we are going to see how it goes this season. It wouldn’t work with a small flock, but I think it could be feasible with a mid-large size flock like ours(18-24 chickens). Here’s our plan:
We love eggs and that is the primary motivation for us to raise chickens(meat being secondary). We butcher cyclically, so that no layer goes past two-three seasons, at which point production would slow down. This means, that at peak production, with 20ish layers, we could be getting 18-20 eggs a day. This is obviously a surplus, but not enough to garner actual income. We have several friends and neighbors interested in buying occasional eggs from us and this was my idea:
Instead of just charging money per dozen, I proposed a cooperative feed system. Our chickens are only fed organic feed, organic produce, and free range on land that is completely wild(never been chemically treated). These “Free Range, organic, pasture raised blah blah blah” quality eggs would easily fetch $7-$8 at a grocery store. So what we will be doing is a trade sort of system: “customer” buys us a bag of our specific feed(about $30/40lb bag) and they get a “punchcard” for 5 dozen eggs. I think this will reduce our feed costs by close to 75%... while still giving us enough of a buffer for eggs for ourselves.
With free ranging and garden trimming snacks, our flock of 22 in the spring/summer/fall takes 10-14 days to go through a 40 lb bag. That’s 3-4 bags a month, if I’m being conservative. With us being able to rely on about 10 dozen eggs per week(also conservatively) during peak season, that is more than enough supply to support the demand of a few “customers”.
With this plan, profits come directly in the form of chicken supplies. You could, of course, alter the purchase requirements to fit your needs... say, if you needed grubs, oyster shell, or other supplements.
You must also consider that you need to be prepared to pay for feed out of your pocket if necessary... and be happy with the savings you make in times of surplus.
Anyhoot, that’s our plan. I also like to factor in that we usually go through about 2 dozen eggs a week in our house. At $7/dzn at the store, we are already almost breaking even... our egg costs would calculate out to nearly $60 per month... and is we sustained a flock only large enough to meet our needs, that’s well within our monthly feed expenditure. So although it may seem “expensive” to buy feed each month, if you’re only supplying a flock that meets your personal needs, it’s very easy to actually break even, even if it doesn’t feel like it. You’re just not spending money one place, and spending it elsewhere.
Also consider the benefits of any other pet ownership... companionship, education, and personal fulfillment. You wouldn’t buy a dog and then think, “Hey, I don’t think it’s worth paying for food for this animal”. Also also, if you don’t enjoy keeping chickens, why invest time, energy, and some money into them at all? Not judging or chastising, just offering some thought processes that might be worth entertaining if anyone reading this thread is just in the stage of considering raising chickens

In short, you’re going to be spending some money... either on the chickens themselves, a coop, a run, equipment like feeders and waterers, bedding, and YES, feed... not to mention the sheer value of your TIME. Ask yourself, is the “cost” worth it?