Have you understood your construction service description?

Congratulations - that's rare! - Five construction performance descriptions at once, all understandable to laypeople, that's a stroke of luck. Or could it be that it was not skimped on what was (too) little included?

This optional or builder-provided or illustration with special equipment is of course annoying when you fall for it. At first, this can still happen or it takes quite a bit of imagination to picture the depicted house naked.

However, this is probably the wrong way here, to point out to the thrifty OP that she has to be careful with a construction service description so that she only gets the standard, for example the mentioned (terrible) surface-mounted thermostats, which here actually also stand for terrible bathroom surface-mounted fittings, like terrible concrete roof tiles, like a terrible gas heating, possibly terrible whatever else...
You do realize that very often an equipment is declared as standard here that actually already represents a very good one? Most built houses simply do not have something like that? Just because something like this is being discussed here does not mean it is the normal standard?

For the sample selection, I have budgeted 70,000 euros

I don’t know if I am actually thrifty.

I have budgeted 70,000 euros for the sampling and hope to manage with that.

Yes, one becomes greedy

It depends on what the base price refers to. Is it a shell house? Should the 70000 also cover extra technology (KfW) and also on-site flooring? Or are they "only" for visible interior fittings?
Everything is relative.
Our catalog house was at 150000. With an open space and (a bit) more technology as well as anthracite-colored windows, we were quickly at 185000. With the flooring, EL, paint on the walls, drywall extras and sanitary surcharges as well as electrical gadgets, we are probably also at these 70000 (I don’t remember exactly). If we had now also changed these horrible white sockets with these surface-mounted thermostats, we would probably already be at 75000

In what year were there still catalog houses for 150,000? Now in 2019 I haven’t seen any.