New construction or buy house, built in '91

Nonsense. There are several solutions for that and they can be explained in 5 minutes.

I'm not completely stupid either, although it would still need to be checked whether a building permit would also be granted for the back part. And the price (or value) would also be affected by the whole thing.

Negotiate down

Whoever negotiates down for me can keep half of the savings. To me, it is then just said: There’s the door, please leave, we sell to someone else (or not at all).

Thank you very much for the many pieces of advice here and please excuse me for not getting back to you all week.

I also suspect that I should not orient myself to the standard land value but rather to supply and demand.

The more we think about it, the less suitable the property is.
The slope at the back has a height difference of more than 3 meters. The width of the plot is about 18 sqm (quite small - OR?), and the size is about 650 sqm, so a long plot.
The height difference of about 3 meters means that we cannot go directly into the garden, which would bother us. Or rather, we would find it better to have direct access to the garden on the same level.

The parquet floor in the existing property still looks good, so I don’t notice anything wrong. However, I did not look under the wardrobe, but ours will later stand there. Parquet is only in the bedrooms/children’s rooms.
Living/dining area, hallway, kitchen, stairs, and bathroom are tiled.

Maybe I should try to finance in a way that allows us to already renovate the bathroom and heating now. However, that would mean that we get a worse interest rate, so I have to calculate what that means in euros.

Best regards
Peter

I'm not completely stupid, although it still needs to be checked whether a building permit would be granted for the rear part. And the whole thing would also affect the price (or value).

This also needs to be checked/clarified at short notice. If the plot layout does not allow for 2 houses side by side and one behind the other cannot be built because the rest is not within the building window, then the rest is garden land and thus the pricing of ~80€/m² for the entire 1200m² is up in the air, meaning: you pay the building price in the front and the garden land price in the back, ergo significantly less than the 100K€ you estimated. If the seller does not accept that, you go home and that's it – unless the 80€ is already the mixed price. Then you have to know what you do with +600m² of additional garden or whether the plot is worth that much to you. If you can’t use the additional garden land, then it simply isn’t your plot – end of story.

Whoever negotiates that down for me may keep half of the savings. To me, it just means: There’s the door, please leave, we’ll sell to someone else (or not at all).

Negotiating down is very simple: You arrange another viewing appointment with an expert, discuss the property with the expert, and then together with the expert determine how much you can pay for the house without breaking your financial neck. If the house still comes into consideration after the expert’s assessment, you submit a written (!!) offer and wait to see what happens. If you are skillful in negotiating, you can also do this orally, but you need to have experience for that.

If the seller’s price expectation (for you) is unrealistic, you can only wait until the price drops, i.e., let time work for you – but still submit the offer, always in writing. If someone else pays 50K€ more, then so be it – but it makes no sense to pay a price that is unacceptable for you. Then the seller is happy, but you go broke. If that’s the case, then it’s simply not your house; no big deal – there are others.

Best regards Dirk Grafe