We did this for my wife right before the Pandemic. Luckily we already had a 12 foot by 12 foot cement pad in our backyard. The building itself was 10 feet by 12 feet and cost $5000. Then we had to install insulation and drywall which was another $1500. Then I had a single 20 Amp power line installed and that cost another $1000, but I also had him do some other work and I assisted with the digging of the trench. I think we were at around $9000 all in with it. I checked with the company and that model of building we got is around $8000 now, so maybe around 60% more now?