Lots of good info up there.
You have to consider everything.
As Seatrout00 mentioned - grow your own feed is nice but with layers and meaties - it is more as a supplement. Your birds NEED proper feed for their age and purpose or you will have some sick birds!
I live in the PNW and layer feed costs generally 16-24 bucks a bag (40-50lb depending on what you get). Organic is even more - about 2x)
my 4 birds eat about 1/4 cup per day per bird on average. they are standard layers - although the runt eats more then the others (that chunky cheeky chicken).
I supplement with treats from my garden (not for the chickens) they get plenty of weed and veggie scraps.
I also purchase mealworms at about $4/mo (just started on growing my own colony - so that expense will be eliminated)
Bedding used to be shavings which cost $8 every 2 months or so.
just switched to a sand system in the coop which runs about $3 a month until I can find a bulk supplier of good sand here.
It is the hidden cost that will bite you - you WILL NEED a 1st aid/medical kit!
That ran me about $100-200 bucks.
If your bird gets ill - the vet will be EXPENSIVE starting at about $40 per visit (not including any tests, meds or procedures)
1/2 of my girls got bumblefoot from (1 puncture and 2 cuts) injuries obtained from foraging in our wooded areas.
That treatment cost about $200 - that was without vet care (just advice from one over a phone call). Not to mention the TIME it took to treat over 5 weeks.
Then are you needing power for heat or light or (A/C in some places)? factor in the electricity or solar power battery costs.
If all is healthy - regular daily (food, water and cleaning) - they cost about $2.30 / week.
They lay about 18 eggs a week (more when my PBR was laying) during peak season. = @ 25centsper egg (the going rate here for local free-range farm eggs) = $4.50 produced a week (I used to buy an 18 pack a week).
That means they cost me (in optimal conditions mind you)...
...
- $2.20 per week yes NEGATIVE $2.20!
so... after all the stupid start-up costs, maintenance, upgrades, medical costs and treats - hopefully we will break even over the lifespan of the girls.
Of course my girls will retire here (not killing them after egg laying slows).
They have become our pets that happen to lay us breakfast and baked goods ingredients.
good luck