Hm, so according to the overview values in Boris, I come to about €120,000 for the building plot.
Detached single-family house, just under 160m2 on a 350sqm building plot
Solidly built house with basement, meets KFW55. The purchase price includes the house completely ready to move in (incl. floors, walls, bathrooms, garage, garden layout).
Assumed land price: TEUR 120
160 sqm GF costs - with classic architecture - TEUR 240
Usable basement: TEUR 45
KFW 55 (incl. basement; belongs to the warm envelope due to technology): TEUR 15
Painting/floor coverings (normal): TEUR 45
Access road: TEUR 15
Outdoor facilities: TEUR 15
Finished garage 2.96 x 6.00 m, incl. foundations: TEUR 6
Additional construction costs: TEUR 40
All in estimated: TEUR 541
However, that seems too low to me. I will ask about it.
For a "standard equipment" it fits; the question is what the provider understands by "upscale" and _where_ the plot is located
Rhenish regards