Or, if you're starting with chooks, do what we do and go to a battery hen place- the chooks are very very cheap, just over a year old and would be killed because they can no longer lay 3 eggs/day. We've got most of our chooks from that place and they are the most lovely creatures, learning how to walk, roost, peck and scratch at the ground ... they now greet us at the gate and follow us around the yard ...

Better homes & garden magazine has some great coops for DIY, or try Organic Gardening Magazine as well.