In reply to pheller:
It's a little hard to compare. It's dependent on region, but also building size, clear spans, etc.
In GA (where Poopy and I both live), metal buildings are common and cheap. About $10 per SF. A similar wood shell only would cost more like $20-25 per SF.
However, that's about 1/4 of the total costs. You still have to add electricity, plumbing, finishes, HVAC, etc to make it a residence.
Those items will cost more in a metal building. At least 25% each. So, you save money in the shell, but spend it in the finishes. You will also spend more to heat and cool a metal building over time.
Wood buildings lend themselves to DIY labor better.
If you want a building with 12' eaves, metal is easier. If you want large clear spans, metal is easier until you get very large and need an engineered foundation. Then metal is much more expensive.
A metal shell building will generally have only a couple crappy windows included in the price. A wood shell building will generally have more windows of better quality. Same for the doors.
A wood frame building will have superior insulation- it is designed with cavities that enable proper insulation. A metal building will generally include a roof, but it will be exposed screws. These are prone to leakage. A standing seam metal roof will double the cost of the building. A wood building will generally have asphalt shingles.
A later addition to a metal building is a big no-no. They are engineered to very close tolerances- you can't add load to them.
The recent tornadoes in my town flattened a lot of metal buildings. The wind pushes through the large roll-up doors and pressurized the building, and it blows out from the inside. Wood frame buildings are more wind resistant.
Everything varies. I'm talking basic normal stuff here.