I am in the process of building a 36x64x16 with two 12x14 overhead doors and a man door on one end, 18x16 split slider on the other. Best price I was quoted was $28,000 for the shell, $8,500 for concrete, and $10,000 for site prep.
I ended up going with a DIY pole barns kit at $16,500 for the shell (minus overhead doors) and $3,500 for concrete. I'm doing it all myself (had some buddies help with trusses and roofing). I couldn't believe how much money they wanted to move some dirt, nail some sticks together, and spread some concrete so I decided it was time to go all in. I now have a 85 John Deere 410B backhoe (I built a set of forks, a 14ft boom pole for forks, and thumb for the hoe), a 89 Dresser TD7E dozer (had to replace the undercarriage), a Grove scissor lift with a 20 ft x 5 ft basket (had a blown duel fuel Kubota that I replaced with Kubota D722 diesel), and Case Ingersoll 444 (had a blown 14hp Koehler gassed that I replaced with Kubota D722 diesel. I also built a custom CAT 1 3-point for the back to pull a landscape rake). In the tool department, I didnt have much for construction tools (never did any construction before this) but I did have mechanics tools. I now have everything needed to build a barn and all the power tools are cordless.
I'm still way under what the contractors had quoted and I was able to get all this equipment and tools. If I can bring myself to sell anything once I'm I really be doing good but, after having the equipment, and knowing it already paid for itself, I don't see it going anywhere.
When I started the project I was skeptical about it not being big enough but everyone told me I was crazy. Needless to say, here I am about 85% done building it and I've already ran out of room.
If I could go back to before I started the project I still wouldn't hire a contractor. On a side note, a buddy of mine was having one built (told me I was crazy for taking on such a big project I knew nothing about) and about the time they got the trusses up, the wind blew the whole thing over.
One thing to remember, nobody will care about the quality of construction of your barn more than you.