I also am in the planning stages of a new outdoor aviary for my birds, which range in size from a very large, 900-gram, Grey to a little parrotlet (not to be used at the same time, obviously). I already have a pre-made aviary (the 6' round one). However, it's getting old now (about 12 years), with a couple of popped (repaired) welds, and I'd just like a newer, larger, nicer looking place. I have a big, covered patio so my aviary is protected from the worst of weather, but it is exposed to some glancing rain, ice, and sun.
I have been looking at the A&E rectangular one, which is powder coated and can be ordered in the half-inch bar spacing. It's not really for full-exposure outdoor conditions but I think it's going to be fine on a covered porch, next to a house. I explored having my aviary custom built but my cockatoo is a complete woodchuck so wood would be totally out of the question, and stainless steel cloth is extraordinarily expensive in the size I would need, not to mention finding someone with parrot understanding and ability to build this aviary to avoid physical injury to the birds. I'm also just not willing to risk the zinc issue using other wire (although my city's zoo uses normal, zinc-coated chain link for its outdoor enclosures for parrots). Acid wash or not, I just don't want to use anything with zinc.
So, you might want to check into some of the ready-made aviaries, as well.