I honestly don’t understand why some people insist on building everything themselves. Sure, it saves money, but you have to understand what exactly you are saving. In this case, I only see saving money by spending your own energy, health, and time. Maybe not all companies provide assembly and installation, which is strange, but these specialists https://www.uspatriotsteel.com/metal-barndominiums/ can help with that without any problems. Other than that, these are turnkey projects. So the difference from the original estimate should be minimal.