What do you intend to do in said barn?
Ordinarily, you can't just take a barn and go live in it. Barns are built as "structures of low human occupancy" and get treated differently in the building code. So you can't just move in, so to speak, you have to make sure that a bunch of things check out, particularly electrical.
If you can do a lot of things your self, and have somewhere to live, converting a barn to a living space is a terrific project.
If you just want to upgrade the barn, then the first thing you need to ask is why... why this barn? Why not just build a new one from the ground up?
Budget? Twice what you're thinking. It always is.