FWIW, I have a pole barn that my dad and I built in '89, and it's still in excellent condition. The big expense was the concrete (it's at least 12" thick, reinforced), but a buddy of his who's a general contractor helped with that. The metal was factory seconds from Star Metals in OKC and the roof trusses were from a place on the east side of I-35 just south of the Canadian, but I don't remember where he got the utility poles (maybe from OEC).
If you can do the work yourself, you can often get a screamin' deal on a used red iron building. When a local church built a new sanctuary a few years ago, my dad put in a sealed bid for the relatively new 40x30 red iron garage they had on the site. I don't recall how much it was, but it was less than $6K for the building, the plans, the electrical (including lights, switches, conduit, etc), and even the pipe rail fence that surrounded it. All he had to do was take it down and get it off the site by the time they started their construction project, and he did that pretty much singlehandedly.
At least 12" of concrete? That must be some really heavy stuff that is parked in there.
My dad is an engineer, and he overengineers everything. He didn't want anything to be able to crack it.
I would say so.
