I know materials are up since I did mine, but I have roughly $16,000 into it because of doing 95% of the work myself. The only things I didn't do, were auger the holes in the ground for the poles & the concrete floor. That $16K includes all of the wood framing & the 2 steel I-Beams, roofing, siding, (cedar in front, vinyl on the rest) electric, overhead & service doors, & the concrete. (1997/98) I also included maybe $1000 for the timber retaining wall, & some of the crushed stone. A lot of the fill, about 120 cubic yards, I got for free from my boss.
With the hurricanes recently, the building supply industry has a reason to raise prices even more. (Legit reason or not, it's been done in the past.) By building a pole building I saved at least $6,000 to $10,000 minimum, based on foundation quotes I had received. The garage is 36 feet across the front, & has an average depth of 22-1/2 feet (810 sq. ft.) I forget what the area is on the second floor, but it's just a little less, maybe 600 sq. ft.
Just as a note, I got estimates in the early 1990's for a complete 24'x24', 2 car, 1 story building for $28,000 from a reputable builder, & another estimate for $6000 from a newspaper ad. Prices still vary today.