Looks like you're talking about $22.57 to $32.98/sf. That seems low. I am finishing a 1,000sf race shop and I'm closing in on $100/sf. Steep roof, scissors trusses in half, storage in other half, in-floor heat, toilet room, three garage doors, two man doors, five windows, lots of concrete for parking the motorhome, suburban, and trailer.
I went with 9' walls and scissor trusses over where the race car will sit. 9' wall was over kill. If I did it again, I would go with 8' walls. I neglected to put a pencil to it, but all the costs cascaded because of the higher walls.
24' is just deep enough. My building is 42' x 23'-9"; zoning is holding me to 1,000sf, I wanted room for four cars (or one stall to work on race car, two more stalls for cars--but then wife wanted a "toilet room" ... so now I have one stall for race car, one stall for another car, and a short stall for a short car or machine tools).
You probably won't be able to get a crew cab pickup with long bed on the garage. My race cars are 17' (m/l) long. 24' deep less 6" walls (12" total) would give me 2.5' on either end of the cars. Trust me, that is barely enough, absolute minimum.
24' wide with room to work around a car (jack it up) have a work bench, shelving for stuff, and then room for anything you remove from the car ... 24' is minimum. Can you make it any wider? a touch deeper? or are you limited to 24' x 24'.
You mention gas to the garage. Are you putting in in-floor heat? I don't think that is in the prices you've been quoted.
I put the trusses in because someday I might put in a lift. Everyone, I mean everyone, is telling me to put in a lift. Many of my racer buddies have a lift. I don't. Been working on the heavy NASCAR stock car for 10 years. Jack it up, roll around underneath it. Works for me.
Rather than 9' walls, put the scissors trusses in. What kind of vehicles do you plan to work on? With the scissor trusses, I think you'll be surprised that you can have a lift and still get a tall vehicle up in the air.
I was lucky. My neighbor is a small residential/very light commercial contractor with long time working relationships with good subs: plumbing, electrical, excavating, and concrete. He, his FT employee, and their PT third guy did all the carpentry, roofing, and insulating. I did the rough and finish electrical to the panel (electrician banned me from the inside of the panel). Rest of the subs did a great job.
You need a small guy. Either you general it yourself (get the bids from the subs, organize everyone, schedule everyone, etc. which is a reasonable amount of work) OR you pay someone who will do this for you. You don't need a guy who does $5 million worth of business a year. I think anyone who normally does small construction/remodeling can do this.
A local lumber yard might be able to give you some leads, or a local electrician or plumber might be able to give you some leads.
If you're working with someone you don't know ... a very detailed set of plans is essential so you get want you think you're getting and the "contractor" clearly knows what you expect.
Good luck! Keep us posted.
