I myself do a lot of improvising on items and recycling items that can be reused from brooder to coop, to help keep down cost of them, mine don't like fancy stuff as long as they got a place to roost and lay they are happy campers and a Happy hen produces. Wish this article would have been written before I started and we built them a nice insulated secure coop that they hated and only time you could get them to go into that coop was if they wanted to brood. would have saved a lot of money and work.
Great article, do wish it mentioned heat lamp alternatives!! Maybe a link to MHP (momma heating pad) which can be as simple as a heating pad (as long as it will go 24/7, no auto shut off) over a frame for holding foil/saran wrap on a kitchen cabinet door, zip ties and old hand towels/pillow cases - or heaters like the sweeter heater or brinsea (not as cost effective).
I found this easy to read. It's a shame the prices are a bit out of date.
If you are planning on taking your chickens to a vet should they become ill, or get injured, then $10 per month isn't likely to cover the vet bills. $10 per chicken per month would probably cover you for two vet visits a year for nothing too serious.
I found this to be about right for me during the winter, being they free range summer time I spend hardly anything. I found you can buy open bag products for 1/2 the price or less at some stores. I've gone from $60 a month to $20, I just use a two large trash cans to hold the food. One for chicken scratch and one for layer pellets.