Financing land and house? Taking out a mortgage? Construction costs?

I took a look at it. I can't understand why he installs the device for the price including materials. After deducting materials and labor, he doesn't make any profit. You should notice that too.

But maybe you don't care

Of course the good man makes some profit. He was just honest and said that he is building up his business and gets paid for his craftsmanship. There's a small markup, but only minimal. A craftsman is not a dealer either. So I am satisfied, he gets the maintenance contract and will be recommended if we are satisfied later.
You wouldn't believe how cheaply these devices are distributed by wholesalers.

Dear community,
since you have helped me a lot to organize my thoughts, I am getting back to you one last time. Meanwhile, we live in our beautiful house for us. Of course, some things are still missing (paving the driveway, splash guard around the house, terrace), as is usually the case with self-contracting, but all in all we live very nicely.
Somehow everything worked out after all. We did not have to give up anything we absolutely wanted, I love the wood-aluminum windows in oak more and more every day. The front door made of oak and corten steel with fingerprint is brilliant.
As information for all future builders: per square meter of living space, we ended up at about €2800 including garage, without basement, in Bavaria (unfortunately rather expensive region).
Many thanks to everyone who participated constructively in the discussion, the input was valuable!

Oh yes, the controlled residential ventilation even stayed within the budget. Overall regarding the budget: A little increase at the bank (surprisingly uncomplicated), more savings effort on our part, and it worked out. Even the Koinor Epos was included; just had to. should get a commission...

Normally, I always give a like when feedback comes in, but now, after a good one and a half years, to get in touch once...

When I read something like this:

Wir mussten auf nichts verzichten, was wir unbedingt haben wollten, gerade die Holz-Aluminium-Fenster in Eiche liebe ich jeden Tag mehr. Die Haustür aus Eiche und Corten-Stahl mit Fingerprint ist genial.

...then I don’t understand the fuss from back then.
......
A timely response would have been appropriate. Many people took a lot of time,

I considered an interim response to be of little purpose. What use is it to say that we still don't know how it will turn out? Now I know what 90% cost. Six months ago, trying to predict would have been, in my opinion, very pointless. Especially with the individual awarding of trades, you only see the outcome at the end. Now I can finally say that it works. However, only with the ongoing income as a "bonus."

Respondents/forum do not need guidance. It was not about the question "When will my construction be finished," but "we don't know how to proceed anymore." Feedback would be appropriate when continuing, which was questioned.