Affordable providers for building a move-in ready house

Since I assume that by "move-in ready" you also want the ancillary construction costs included... for 250,000 you won't get more than 80m² even with Town & Country or Heinz von Heiden, and that only turnkey, not move-in ready. Forget it.

Town & Country as a general contractor ("GU") that is not a discounter but offers need- rather than status-oriented products is, in my view, a good indicator of a price level that cannot be significantly undercut for "turnkey" with a satisfactory standard – in other words, a benchmark for credible affordability. Significantly lower prices will necessarily have to include an element of wishful thinking.

The OP has gone pretty quiet.
Apparently, the realization is sinking in that it was a crazy idea.

Price-wise, the whole thing should not exceed €200,000-250,000. (Land etc. is of course extra, so.. the cheaper the better)

And how much money is available for the land?
With that budget, maybe it's better to look more towards existing properties.

The OP has gone pretty quiet.
The realization is probably dawning that it was a crazy idea.

well, building a house nowadays for 250,000 is more like a bigger doghouse with a front door

well, nowadays building a house for 250,000 is more like a bigger doghouse with an entrance door

Or you have to do a lot yourself.

But he didn't want that, he wanted all-inclusive ready to move in ;)