Wow, Dave, that looks nice! You're really going to love it!
I never saw this thread before, but just for anyone thinking about it I'll share my experience.
I went with a 24'x36' Outback Steel (brand) building, marketed and sold as a DIY kit. It's a bolt together steel building, clear span and no welding. They are building these things huge now and I hope to build a bigger one on a piece of land one day.
I've got a total of about $23k in mine without my cost for time. I was able to build it over the course of a couple months with one or two helpers and just had to rent one tool, a material lift for the rafters.
I had to hire the concrete (about $6k) and the electric to pass ordinance here.
10'x10' center door, one window, 2 walk through doors.
Insulated with bubble foil (Reflectix) stuff.
8 skylights
full guttering
thick concrete for lift
100 amp electric service.
Very basic plumbing, floor drains and one sink, no bath.
I heat mine with a wood stove and my only regret is not fully air conditioning it (yet).
If you live in heat or humidity and spend much time in it I really recommend this.