I just noticed that you are from my area.
I am currently also in the planning stage but already a bit further along than you are.
A plot for 30,000€ is daring. I wouldn’t know where to realize that near us except maybe towards Limburg, or Seeheim-Jugenheim, Heppenheim area.
Just our plot with nearly 800 sqm costs around 200k including all expenses, meaning land transfer, notary, etc.
Regarding the house, we are still planning, maximum 290 sqm or so. So more than double your desired size.
My wife is not a top earner, but that was not taken into account since my salary is completely sufficient. Of course, it could always be more, but you have to know when to stop somewhere. I’m around 4,800 net minimum. Currently, the bank has approved a rate of 2,500€ with a fixed interest for 20 years at 2.51%. I think that is reasonable.
But I’m only 25, so there is still room for improvement with further training, etc.
If I were you, I would also advise pursuing further training or postponing the house plan if equity is available. Of course, no one can say how prices will develop in the future. In times of low interest rates, it is naturally ideal to build a house.