New single-family house with basement (on a slope)

As a family with a child, we want to build a single-family house south of Stuttgart. We have a plot of land in sight. We have looked at the Flair 113 from Town & Country, as the plot comes with a basement.
Does anyone have experience with this?
What budget should one generally calculate for this? Is around ~400k (house + incidental costs) realistic?
The following should be realized through own work: drywall, electrical work, interior doors, sanitary / tiling, interior plaster, painting, floor coverings.
The financing is to be done, among others, through the L-Bank with the Z15 loan.
Which other construction companies should we look at, also considering the own work?

We look forward to your feedback!

Phew, that's quite a substantial amount of own work.

Remaining are the shell construction, roof, windows, screed. I wouldn't necessarily go to Town & Country for that, try looking for a medium-sized local general contractor who can handle the planning and shell construction quite cheaply on their own and maybe also does one trade themselves (the good ones usually have 2-3 in-house trades, with us it was shell construction, roof, plasterer/drywall). And maybe you simply assign the rest yourselves or have it offered by the general contractor.
GD

Hello everyone,
great tips, thank you :)

Exactly, Town & Country is not a manufacturer of shell houses. There are others. But: For a sloped plot, I always recommend an architect. Especially if you HAVE to build with a basement, it should be checked how the slope can be utilized. On the one hand, the outdoor area is part of the planning, which may need to be retained multiple times and filled up here and there. On the other hand, it might even be advisable to build only one floor (similar to a bungalow) and develop the basement as living space. I consider Town & Country absolutely wrong for that. They do not have the best reputation anyway. Those who can build simply might be satisfied with them; those who have to build elaborately might end up very unhappy with this franchise company.

We as a family with a child want to build a single-family house south of Stuttgart. We have a plot of land in sight. We looked at the Flair 113 from Town & Country, since the plot is on a hillside with a basement. Does anyone have experience with this?

Hillside: yes Town & Country: no And: hillside is always something individual depending on the material you find and the amount to be moved, not to mention the steepness. Our plot will very likely differ from yours. Why I still contribute something: I get the impression that you think a house is a house and can stand anywhere you put something horizontal beneath it. That does not apply to hillside locations if the basement rooms become part of the floor plan and one side connects to the terrain and the other does not. The idea of linking a standard house with a non-standard terrain, upon closer inspection, is a bold endeavor that hardly has a chance to save money, if that is the basic idea behind it.

Slope costs money and slope is not equal to slope.
For us, the "basement" is a living floor and has become the ground floor. Quite classic with entrance, building services, guest bathroom, living-dining room with kitchen. Ground-level access to the terrace.

You have to consider the entire property. How do I position the house, how do I design the outdoor area with as little earth movement as possible? How do I use the basement? If it is empty space it is expensive, if you fill it with necessary living spaces the additional cost is somewhat relativized.