its not terribly expensive to keep chickens alive, but it can get ridiculously expensive to properly care for them. Constantly cleaning pens, replacing straw, broken feeders, waterers, fixing pens, lumber, wire, and then you have feed. Pellets are fine but most chickens will do far better with a little more variety.
I also raise birds for feathers. The feed alone for them is almost prohibitively expensive. So even if you had the birds you might not get the same feather quality out of them.
It definately won't be an enjoyable experience if your having trouble paying for everything.