Start up costs are the most, but they are one time cost. After you get set up, then it's just maintenance.
Coop was an old shed donated to us. Cost $400 to move it
Fencing donated, but spent an entire weekend installing it, then decided to free range them anyway (they eat WAY less commercial feed if they are out scrounging for bugs).
Birds were $39 for chicks (13 total). 4 turned out to be roos. Ate two, gave two away.
I averaged a loss of about $60 a month my first year owning chickens (yes I track it all obsessively). They are laying now and I sell eggs for $3.50/dozen. They also free range, cutting their feed cost in half, and reducing the number of lyme disease carrying ticks in the yard. The numeric value of chickens may not be making you a profit, but if they did not have a higher value than cost, so many people would not own them. You CAN have them pay for themselves though, if you are frugal and don't spoil them and are not picky about how things look. Here are a few ideas about how to be frugal:
-Building your coop you can use recycled materials. Pick up an old dog house, build one with plywood or old pallets. You can even find free paint in the "free" section of craigslist if you want to make it look somewhat nice.
-It is possible to get free birds. Some people get sick of having to care for their flock or they cannot afford to feed them through the winter. BE CAREFUL taking in any new birds. New birds bring in new issues. Lice, mites, illness. A lot of birds have been exposed to Mareks disease and if vaccinated will show no signs but could infect your current flock You can almost always find free roosters. If you do not have a rooster, you can use him to repopulate your current flock by breeding, or if you are not opposed to eating them, it is pretty simple to process them yourself at home (youtube search).
-Free range your birds if you can. If you are worried about predators or cant free range them, offer them leaves, brush, grass clippings and table scraps to help reduce costs of feed.
-Sell their eggs. There is value in eggs that your family eat as well. Track the numbers to see if you are making any money if you like. I charge $3.50 per dozen and $3 for friends and family. If we eat a dozen, I write that down as $3 income because we did not have to buy eggs.
-Sell their compost, or use it yourself in your gardens. I have a small raised bed garden that is thriving on added chicken poo. Poo may be worthless, unless utilized. Now I have turned it into valuable crops and veggies to feed my family or sell at a farmers market.
-Sell their feathers. Chickens will molt once a year. Not pretty for them, but their feathers are great for crafters or fly tyers. Or make some kitty toys with them and sell them at craft fairs or give away as gifts for Christmas or Birthdays to cat lovers.
-They don't need fancy waterers or feeders. Search how to make your own feeder from recycled bottles, buckets, wood, PVC, etc. For a waterer, use a shallow bucket or two. I have spent a lot of $ on making chicken waterers with poultry nipples and buying 5 gallon buckets and they can sometimes leak, the birds don't tend to like them as much (though they do stay cleaner longer). Find an old dog dish and refill it once a day. On the other hand, you can find old buckets, or clean gallon jugs and buy poultry water nipples for about $5 for a pack of 6. Use one nipple spout for about 3-4 chickens. Make one for your own flock then sell one. Similar buckets sell for $20-$30 at the feed store. $5 for the nipples and two free buckets you can sell for $10-$15 each and you made a profit.
-Collect bugs. Put a water bucket under an outside light on your porch in June and collect some great big June bugs for your girls for free treats. Or if you aren't disgusted by the smell, you can pick up roadkill, put it in a 5 gallon bucket with a few small holes drilled in the bottom (open top bucket to allow flies to get in) and raise it about 5-8 feet above your run. Flies will lay their eggs in the carcass and yummy maggots will drop from the holes into your chicken coop. Free protein for them. Yucky though. haha havent tried this one. Set up mouse snap traps near your chicken feed and feed mice to your chickens. Gross again, but they love them.
-Have a work farm. Add chicken poop and veggie scraps and yard scraps to a bucket of worms. Worms make worm castings which is the best kind of composted soil you can plant directly into without worrying about burning your plants with acidity or too highly concentrated nutrients like you do with straight chicken poo. Plus, chickens will love the worms when they multiply.
-Go to the dump, search craigslist free listings and be resourceful.
-If you can help not getting attached to your chickens, cull the older birds (3 years or so) as they slow down in laying eggs and wont earn their keep financially speaking. Older hens will have tougher meat, but can still be used in the stew pot and make a great soup. I know some will be offended by my saying this, but to me, if you eat meat, wouldn't you rather know where it comes from and know that it had a good life and swift dispatch than eat a commercially grown, over crowded butterball that had its beak melted/cut off or pecked by its neighbors and kept in ammonia soaked air?
I know not everyone will enjoy or agree with my advice as many keep their chickens as pets and spoil them. But if you're a farmer and see poultry as livestock that need to earn their keep, maybe some of this will be helpful to you.