Prices are often higher than you think, you notice that quite quickly when you get quotes.
You should already calculate 2200/m2 if you want a bit of luxury... venetian blinds, sliding door, no standard sanitary ware, etc.
Depending on the size, the house costs 350-400k
20k kitchen
10k furniture (open end)
30k double garage (masonry rather 40-45k)
20-30k outdoor facilities (open end)
Plus land.
If you're not building in the last village in DE, you currently never get below 500k turnkey, that's my experience so far.
And there’s no cellar included yet, which also hits quite hard (depending on the plot of course).