Planning a land purchase and a 400k budget for house construction

Good evening dear community,
we are currently interested in a plot of land which is about 1000m² in size and should cost 34k including notary and property transfer tax, but is undeveloped.
Development costs amount to about 25-30k according to previous research.
The plot is to be purchased with equity.
The plot has a slight slope (I am attaching photos) which is why we imagine a partial basement and want to put a prefab house in timber frame construction on top.
With the partial basement, we want to move the technical room into the basement and thus gain living space to save money on living space square meters.
Our budget for house development, basement, and prefab house should not exceed 400k.

What is your opinion on these ideas?
Is this feasible with this budget?

Looking forward to active participation

Regards Marvin

With 400k you can still get something even on a slope. You just have to plan extremely cost-efficiently. Cut the partial basement and plan living spaces in the basement. Don't worry, modern basements have nothing to do with dark, damp cellars. Don't commit to timber frame. Also inquire with local companies. Carport instead of garage. Don't fill up everything in the outdoor area. You could build 120-130 sqm.

Thank you very much for the response. However, we would still have to fill or remove quite a bit to lay a pure foundation slab. The excavation could certainly be temporarily stored on the property and possibly reused later. Do you mean by regional companies to rethink in terms of solid construction?

However, we would still have to fill or excavate quite a bit in order to lay a pure slab foundation.

What means: Forgo a usable cellar and instead have a basement, meaning living rooms in the basement, then a ground floor, and that’s it. Financially more feasible than a 60 sqm tower on three levels.

Yes, also solid construction or small carpentries. Solid construction handles slopes more easily and does not tend to build towers. Small carpentries can score well in the good and affordable class. They don't have to, but they can.

YPG had already written it as I meant it.

I find the wording `"etwas" Hanglage´ amusing, as the pictures show a hillside in two dimensions on the mountain side, which transitions into a one-dimensional slope towards the valley side. On the other hand, it is not clear to me what is meant by "nicht erschlossen": there are houses opposite, and I also see a manhole cover, so most likely only the connection to the property is missing here. To my surprise, given the rural setting, I don't see any power lines coming over the roofs, so they are probably already underground beneath the street. Considering the surroundings, I would not be surprised if the property is not fully counted as part of the interior area.