Surprising price increase just before signing

It bothers me a lot that everything was actually settled and now, out of the blue, the price goes up.

Follow your gut feeling. Just ask for more time to think again and calmly look for alternatives. Or would you definitely build with them if they waive the additional charge? The risk is that they might recoup it in other ways; there are still enough possibilities during the construction phase. There are always some changes for which you then need a supplementary offer.

I have the suspicion that our salesperson always acts like "everything is fine and the main thing is that we can talk about everything," but in the end he doesn’t really care, as long as we sign.

Yes, that’s probably how it is. However, the third conversation or so should already be conducted with the boss/manager, not with the salesperson anymore. He is basically out of the further process.

However, after about the third conversation, it should already be with the boss/manager, so no longer with the salesperson. He is then basically out of the further process.

That was also the meaning of my comment: Schmidtchen would be out of the game with me after this situation, in the next round only Schmidt himself would still be on the playing field, and I would give him one more chance – namely, to stand by his previous word and remain friends.

We experienced two things:
GU 1: informed us at short notice that the price would increase by about €8,000
GU 2: told us directly in the first conversation that a wage increase in construction is due next year and therefore around 7k extra is expected.

I found option 2 clearly more charming

I see it the same way.
If something like that is communicated beforehand, it's a completely different matter.

Let's see what our second provider says.

It is not nice. The fact that one item/service 21 costs more than 20 is somewhat understandable. However, the seller should have communicated that. They could have also said that as of 1.1 we usually raise prices. I have to check how it is with you and by how much. Therefore, it does leave a bad taste. Continue with the other one. For me, he would be out.