Just upgraded my girls from a generic coop to an Aussie style chicken mansion which typified by lots of windows and carbonate roofing.
Paid $120 for the fort, made of hardwood mostly. Picked up the door and windows for free around Sydney during the pandemic renovation boom. Paid $20 for the antique timber ladder which I cut it in half to build the roost bar for the girls. Paid $20 for the used weather boards used for cladding on one side. The antique light fitting was $10, and the awning was $10 too. The most expensive parts would be the chinese antique breezeaway tiles which is worth $100 each. I had them for free some years ago and have kept till now. So all up, it most likely cost around $250 including cement and sand for the footings.
I am very happy with the result, especially the stained glass windows which just look magically when the sun shines through. There are still more to do, such as building steps and chicken run etc. In the meanwhile, I am going to sit back and relax with a coffee in the morning inside the coop.