Is a house for a total volume of 400k still possible at all?

Currently, we also tend to wallpaper the Q2 filling with painter's fleece, depending on the condition, and then paint it with brush plaster.

Can you actually paint directly on Q3 without painter's fleece or anything similar? I don't want anything that has even the slightest connection with wallpapering :)

Also a reason why I am asking about [Streichputz]. What can you compare one with a 0.5mm grain size to? 100-grit sandpaper?

Everything individually is nothing extraordinary. But overall, it’s the complete package. In the past, you would have built all this up over years. Of course, it absolutely makes sense to have many things done during construction—but as a result, house prices also go up. Nowadays, the goal of being “finished” is much more short-term than before.

Retrofitting sockets and cables? Doesn’t sound particularly economical, since you then have to plaster and paint again. I do see a few things that I wouldn’t necessarily install myself, but basically nothing that would make particularly much sense to do after moving in. And in the end, it costs money, one way or another. Whether you finance 10,000€ more or have a slightly lower rate and then keep making changes...

What can you compare a 0.5mm grit to? 100-grit sandpaper?

Wikipedia says:

As a rough estimate for the grit size: Grit size in mm = 25.4 / grit.
;)

So probably mathematically like 50-grit.

I would simply buy a bucket and test brush somewhere.
We've already done that with facade paint as well.

Or, at an Obi (I have three nearby) they even have a piece of "sample wall" with both types, maybe you have that too.

Laying sockets and cables afterwards? Doesn’t sound very economical, you have to plaster and paint again. I do see a few things that I wouldn’t necessarily install myself, but actually nothing that would make particularly sense to do after moving in. And in the end it costs money, one way or another. Whether you finance 10,000€ more or have a slightly lower rate and then keep doing things...

Moooaaaahhh... yes, of course it makes sense to do everything immediately. But there are things that basically have to be done and there are things that are just nice to have.
For example, I count 8 outdoor sockets and 7 outdoor connection points rather as nice to have.
Makes sense to do immediately? Yes!
Should every homebuilder do that? No, not necessarily.
And your argument that you then just take out 10,000 euros more credit fits exactly here:
Houses are also getting more expensive for that reason. People convince themselves every additional euro is totally sensible. The thread question is whether it’s still possible at all to build a house under 400k.

It doesn’t stop with the electrical installation. There is optimization potential in every room that also totally makes sense to commission directly during construction and increase the credit for it.
Here KNX, there a few more windows. The floor can also be done immediately in top first-class quality. Who wants to replace it again in a few years?

I would have no problems justifying the costs of a 1 million house reasonably with arguments ;)

Ui 50er I would find for interior walls already quite rough. Damn, I guess I have to learn how to wallpaper. I'm pissed off.