House price reasonable?!

Invest some money and get an expert. They can give you much, much better guidance for this decision than any forum post here. Also remember that, for example, you exclude the kitchen from the calculation of the building value for the property tax.

That will be difficult, because there are hardly any building plots and if you find any, they are relatively expensive.

And that is exactly why people also decide to look at used properties.

Check the real estate portal in your area for comparable properties, then you will know the value of these properties on your market.
The gut feeling has to decide whether you want to live there.
You also have to make compromises in a new building: one person makes them with the living space, another with the appearance, the next with the technology.

I could not detect any gold rush mood.

Regards Yvonne

There is also no gold rush mood, because I know the owners. [Immoscout Erstbewertung] says €367,000

There is also no gold rush atmosphere, because I know the owners. Immoscout initial valuation says €367,000

I did not suggest that you should make an appraisal, but you should take a look at what else is being offered to you. If everything is €100,000 more expensive or everything at this price is 20 years older, you can decide for yourself whether it is a good value property on the market.

Without being an expert, I can tell you with great certainty that buying a house in this price range without an expert would be grossly negligent. The expenses are too great for your wallet.

Without having read the entire thread. Is there already a bank that would accompany the purchase (assuming the buyer will finance part of the price)? What does the bank say about the requested price?