Expansion house or turnkey

A layman, even a self-proclaimed "universal" handyman, takes twice to three times as long as an experienced person, needs the necessary machines, messes up his car while procuring materials, twists and mistreats his body, and bears all responsibility. Without any warranty.

Only having Town & Country do the shell construction should be possible. A friend did the same.
I don’t know if the same contractor is active in MSP as with us. Here you don't hear anything bad about Town & Country.

You have to procure the material yourself. I don’t think you save money doing that.
The immense own effort should not be underestimated. Roughly estimated, we needed 1800 to 2000 working hours for the interior finishing. That would be one year full-time at a 40-hour week.
Acquaintances have been spending every free minute on the construction site for almost a year, including father, father-in-law, and friends. What started as a lot of time turned into moving into the construction site. Basically, it is doable. Some people here do it.

Every paid craftsman hour minimizes the savings.

Not every craftsman delivers poor quality, just as not every own effort is error-free.

I even prefer to get the materials myself rather than have something knocked into the house at turnkey prices for which I can get better quality...

What do you mean, for example?

2 years would hardly be worth the savings for me in terms of family time