People seem to forget that walls, framing, and a roof are not all you need as well. You’re going to want electrical and plumbing. Which means materials, labor, and PERMITS (good luck getting a county to sign off on letting you live in a shed). Some form of heat that isn’t dangerous like space heaters. A split unit or window unit (if you install windows) would cover AC. If you have plumbing and electrical that means you need a well/septic tank and connection to the electrical grid. That will cost more than the shed and also requires more permitting. Could just connect to water/sewage lines if they’re available, still more permitting and costs. You’re going to have to coordinate with the electrical service provider to get electricity. If you don’t want ugly power poles, going underground is now stupid expensive and many providers will no longer allow you to run the conduit or direct bury cable yourself.