It depends on how you intercept and how high. There is a very wide range from "we just trim it a bit" to self-made retaining walls, L-stones set by a garden landscaper (because too heavy to move without an excavator) to natural stone dry wall. Since you see it from your own terrace, you tend to prefer nicer solutions, which are usually also more expensive.
Ultimately, though, such things reduce the financial advantage of "building without a basement." And at some point, the question is whether it is still a good ratio to pay 50% or more of the basement price to end up without a basement. You will have to make that decision yourself in the end. I would also ask again whether you really only need 80 sqm including basement and storage rooms. Beyond a certain threshold, building smaller only becomes slightly cheaper, because you still need a front door, heating, a bathroom, a kitchen...
For those born in '89, the question of family planning might also arise.
Good points. We are aware that the savings from less living space do not scale linearly with the reduction itself. But we have really thought a lot about how we want to live and this is what came out. Even if there were more space for free, we would probably decline because what use is more space if I don’t need it? Stuff stored that I also don’t need? And I think we certainly won’t get a basement for free on this slope and therefore even a small saving is a saving.
We are aware that this mentality might not be understandable for many, but it makes sense to us. Family planning is also completed.
Nevertheless, thanks a lot for the food for thought, it is very valuable.