Our family project to build a coop and raise chickens for eggs had one major requiremment
It had to be
so, we used mainly scavenged wood, from freecycle,a bunch of printers pallets from a local copying store, and alot of friends helping out. The doors and windows were all Freecycle. The only stuff we bought new was 2X4 and metal roofing. The whole thing cost us 150$ total
The walls are insulated with various stuff, from a bag of packing peanuts, to scrap material from a seamstress, to some leftover pink insulation, then painted. The base was trimmed with extra shingles from a friend's roofing project. The fencing from the run was leftover from a vet friend's quarantine run project.