First know the cost of lumber has recently REALLY dropped. I saw a graph the other day and will look for that and post it.
We built a big barn coming up on 3 yrs ago and our builder said it would have been 30% higher if we’d done it in the past couple years.
So if you can wait just a little bit you might really save money.
You definitely want to build Amish if possible. The cost is so much lower. And yes, the excavating, pad, utilities, lights, base, footing are all on top of the structure cost…but you know that.
I know of a local barn built by the same builder and something like 80x180 but not 18 ft high and the shell was $100k but that was 5 yrs ago.
Our arena is 18ft high and 72x144 but has two wings off each side of it at 24x166 and lots of concrete, permacolumn posts and lots of other add ons so I don’t know the cost of the arena alone.