How to afford building a house and buying land today?

It is definitely possible to build cheaply.
A good friend built a house for his sister and her child. Including the plot and incidental costs as well as the exterior facilities and 200 sqm of living space, they completed it for 230,000 euros.

But at this price, you really have to do a lot yourself. Starting with the earthworks, sewer connection, with two bricklayers and three free helpers from the circle of friends for the shell construction, unloading bricks yourself with the wheel loader (it costs quite a bit per load if you don’t do it yourself), exterior and interior plastering with only two plasterers and again two or three helpers, roofing done yourself, discounts on windows and doors due to personal connections... etc

Correct!

I have mentioned that I am a civil engineer working as a site manager in a construction company.
I have a network of suppliers, a structural engineer, etc., and I can have pipe materials, earthworks, and the base slab all done at favorable prices without VAT through the company.

Additionally, the company employs 140 skilled workers. This includes everything from pipe fitters, painters, to stonemasons.

Yes, and what about all the additional costs, like incidental building costs, customs clearance, garden, garage, etc.? That does NOT add up. Do you know what the word "turnkey" even means? Look at the existing houses you can get for €250,000. Does that correspond to your dream home? If yes: problem solved

You can approach it from two sides: What can I afford, what do I want.
Your financial situation is – sorry for the choice of words – very bad if you expect a decreasing salary and voluntarily provide family support. There really is nothing left over and I understand why you want to stay under €250,000.

The post does not reflect at all what I meant .......and besides, please note the beginning again: €250,000 PLUS incidental building costs.

Garage: First park on the street. I’ve been doing that for 16 years.
Garden: Does that cost €20,000?
Is it bad to provide family support if one’s own mother lives in old-age poverty? A disgusting statement from you!
I am NOT expecting a decreasing salary, but a lower household income due to children and then my wife working part-time. Please read more carefully here as well and express yourself more precisely.

Yes, it is!

Now it's getting a bit childish.

without VAT

Without VAT is not legal and is tax evasion! I do not participate in such invoices.

I have already stated that I am a civil engineer working as a construction manager in a construction company.
I have a network of suppliers, a structural engineer, etc., I can have pipe material, earthworks, foundation slab all done at favorable prices without VAT through the company.

In addition, 140 skilled workers are employed in the company. From pipefitters to painters to stonemasons, everything is covered.

Are they doing all that for free? I also hope you are not calculating with undeclared work there!
Cheaper I can accept. Still, you need the material etc.

But you did not speak of any of that before, instead of a turnkey house for 130k.
That will not even include the foundation slab, let alone additional construction costs.
How many square meters is it supposed to be?

They do all that for free? I also hope you don't calculate with undeclared work! Cheaper I can accept. Still, you need the materials etc.

Not for free, but cheaper! Example: list price of a concrete: 120 euros, purchase price for the company: 65 euros. Material: also cheaper, no list prices

VAT: I recommend dealing with input tax for companies. But that should not be part of this thread

VAT: I recommend dealing with input tax for companies. But that should not be part of this thread

You are a private individual. Whoever sells to you (companies) must remit VAT. Whoever does not do so acts illegally.

What I often find missing in the comparison between ownership and renting are the costs of ownership. Starting with interest costs, notary fees, etc. And the absolutely most important thing: maintenance. A property is basically not suitable for saving. Here a faucet, there something for the irrigation, the lawnmower, etc. etc. Yes, with renting one must expect an increase sometimes. But if something is broken, I call the landlord and that’s that.

We also have a single-family house. But with a net income of over €4000 and two children, we limited ourselves to a rate of just over €800. We searched for corresponding properties. A new build was out of the question due to construction costs.

Freedom, besides time independence, is also financial independence. I explicitly do NOT want to have to hold back or even calculate when it comes to daily conveniences. After all, I am living now. Who knows what tomorrow will bring? And having to worry about whether one can/wants to eat out for the third time in a week? No thanks.