Common belief is that nine full size chickens will need about 36 square feet of floor space inside the coop. It's possible to make do with less, but not much less. Good coop kits are hard to find, especially at a low cost. And for those same nine chickens, you will need a run of about 90 square feet, which can also be pricey. Buying feed for nine chickens will run about $20 per month. The cheapest part of having chickens is often the chickens.
But if you really want chickens, look for coop plans that are big enough for your nine chickens, take them to your lumberyard and get an estimate of the material cost. They may also recommend a carpenter to build it for you.
I say all this based on the nine hens and one rooster that I started with last May. I have thoroughly enjoyed them, but they haven't been inexpensive.
Good luck.
