I paid $26.66 a ft for a large finished shop, 12ft ceiling first floor, 8ft second floor, with everything and did only some of the wood work, floor, etc. That includes it all, heat/air, vinyl siding, insulation, lights, wooden floor, lifting beam, windows, etc, etc, etc......
The electrical was the real killer, had to run power to the shop and then both 110 and 220, 200amp downstairs, 100amp upstairs, it cost 10k just for my electrical work and lights. Duke power would not give me a separate meter and would only run power to the shop if I agreed to pay a commercial rate, which is 50% higher than residential. So I had to pay someone to run it for me and use the meter at the house.