You can buy prefab homes, pretty much like shopping at ikea. They come in a box with instructions on sticking it together! All with that little hex-wrench thing ;). All you’ll need is septic and utilities.
Some are pretty sweet looking but expensive. These guys will price in the permit process for you. I like the steel frames because they won’t burn, won’t taste good to termites, won’t fall over in an earthquake, are electrically grounded, and can stand 200mph winds.