Depending on how handy you are, your time, and your wallet, a lot of it you can do yourself.
When I bought my place, there was a 30x40 pole barn shell, dirt floor.
Had concrete floor & roll-up door put in, did wiring, insulation, lights & a drop ceiling myself with a buddy.
Ran out of space in a couple years, so did a 20x36 - would've been bigger but had limitations (location, access, property line)
That one I did mostly by myself except clearing, setting posts & roof framing, and concrete.
Concrete after building was up, no floor leaks in either.

Probably wise to check other recent local projects and talk to building owners.
We did an addition at the last shop I ran - Steel Structures America - took forever, and difficult at every turn.
But a lot of folks had good experiences with them elsewhere.