Cost-effective building without loss of quality, architect's house

For 100k you won’t get the entire plot terraced and secured.

Not the whole plot, but the building site + a terrace for the summer should probably be doable? For 100k you can already get quite a bit of excavator time and stones, or am I mistaken here?

Nearby, a slope was recently dug away to create parking spaces for 5-6 cars – including a 2-3 meter high wall for slope stabilization.

I’ll ask what that cost.

If you plan something like this cleverly, it often works with very little slope protection. That should be handled by the house.

100 k can be enough for house and terrace + a little more If you can't dig deep, an elongated building structure might make sense. Retaining wall depends on what material you want.

Not the entire property, but the building plot + a terrace for the summer should probably be included?
For 100k you can already get quite a lot of excavator time and stones, or am I mistaken here?

You don't just have the excavator. The entire construction site logistics are much more complicated in steep terrain. It starts with the roads being much narrower than in normal residential areas and the curves often tighter. A semi-trailer truck often cannot be used, and everything has to be transported with a three-axle truck half the size. Dumping materials simply by the roadside is not possible; the material must be transported away immediately, often by crane. Crane space is also an issue; finding 4x4m of level ground is difficult, and you’re already obligated with the first shoring. And so on.
We are often in Upper Valais, where everything is steep away from the Rhône as well. Two or three years ago, a house was still being built in the settlement, and the concrete mixers had to reverse through the settlement uphill. They definitely charge extra for the additional effort.

Just ask the local construction mogul for a standard package for you.

He can surely do it cheaply, and if you're lucky, you can use his entire planning structure - that's the much bigger saving than reinventing the wheel with your own architect...

Square meters save as well, but you have to be modest there.

Tiles, sinks, toilets, window size, and other selection stuff don't really offer any savings - if you keep it normal, it just won't get any more expensive....

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We are more often in the Upper Valais, where everything is steep away from the Rhone as well. Two to three years ago, a house was still being built in the settlement, and the concrete mixers had to back up through the settlement. They definitely charge accordingly for the additional effort.

Definitely and definitely with an additional guarantee...
I just checked, the civil engineer charged us a flat fee of 1,000 EUR due to the narrow access... we are located directly at the intersection of two 5m wide roads, and during the construction of the shell structures in the new development area, it was even easily 6m wide...

Brace yourself...