Our starting cost was the cost of two rolls of chicken wire and staples for the staple gun. Everything else we used to build our coop was already on our property. We used an unfinished shed that the previous owners built, some recycled pallets, and wood and 2x4 poles that we found on the property. Your cost may vary depending on how much recycled material you can come up with. Pallets are a great, often free, source of building materials, you can take them apart or use them as is for fence construction like we did. A chicken coop doesn't have to be big, just big enough for your chickens to roost, nest, and you to easily clean.
We feed Nutrena flock raiser, it's, what, $16 a bag? We buy it about once a month and feed the chickens kitchen scraps too. If you're going to have a rooster or chickens that aren't laying frequently, get a starter, grower, or all purpose flock raiser. Layer feed has a lot of calcium and that's apparently quite bad for any chicken that is not actively laying (like roosters). We free range when there isn't snow on the ground and feed costs go down, down, down.
We got our chickens free, but I've been looking into Jersey Giant meat chickens and they're going for $2-2.50 per chick seems like, and that seemed pretty on par with that particular hatchery's stock for layers too.