Living down here in Arkansas you dont see many wood truss pole buildings, but I see tons and tons of steel truss ones.
In Minnesota its just the opposite. Up there I could count on one hand the number of steel truss outbuilding ive seen, and thats after you remove most of my fingers. I would be darn surprised that building is anything other that a pole barn with wood trusses.
As suggested, the posts are likely 6x6, 6 to 8 feet on center, trusses 6 to 8 feet on center as well. In Minnesota most buildings like that are built to 40 pound roof load and on a tall building like that, with code requiring a 100 mph wind load, there will be a lot of diagonal bracing. When I built mine (36x48) I had 12X12 doors on each end, and was required to put 2 2x16 headers over each door, plated to the lower truss beam.
I would NOT raise the trusses off the tops of the posts, you will weaken it. If I did anything, I would just splice them. Cut the post a foot or so up from the ground, raise the building the 6-8-10 inches you want, and set it down with post sections cut to length and fish plate the posts with 3/8 steel plates through bolted.
I see that house has been on the market since April, and they been dropping the price 10-15K every month since June. Bet they drop another 10 by the end of the month? These are motivated sellers. Not trying to be mean, but I would offer 125 on your contingency sale. And if you need to sell your home, have you had any realtors out to do a cost analysis? You may be in for a real shock. These people started at 200K 7 months ago. Likely that was a 400K plus home just 3 years ago. Our sons house in Moundsview just lost another 35K on its tax appraised value. By Buddies house up in Coon Rapids is now appraised lower than what they bought it for in 91. Its a real kick in the pants. We wont even talk about the house we had, thats an even sicker deal. My Dad and I had a place in Nowthen, just west of this place 10 odd miles. Land out there went like a roller coaster. 2500 acre in 89, 30K acre by 2001 ish, now its back to 2500 an acre. Even so, id rather have land over a house.
edit; I also agree with RJ, work with someone local. All the trouble were in was caused by lenders lending to people with questionable income (or no income!). Theyve tightened that up. If you have any kind of credit, verifiable income, and a pulse, your golden.
The reason I say 125K is because thats the current trend, and likely where it will be in a few more months. And lets all be honest, its probably going to keep going down for a long while. A year from now you could be well upside down even buying at 125.