House purchase single-family house built in 77 how to assess?

How is the condition now?

From your perspective entirely. Is it the dream house? Dream location?

Or are there alternatives? For you? Are you very limited to one place of residence? And is that the best location? Or do you have several places in mind? Then I would wait a little longer. Surely much more will come onto the market in the next few months at lower prices (especially in the age group of buildings), due to energy costs.

I would recommend taking the building surveyor along directly for an agreed fee. He will tell you fairly accurately what needs to be done new on the hut and can estimate the costs for you.

I have another appointment soon (with the fortunately sunny weather), so just briefly: 1977 is (I have not yet read any statement about the manufacturer) not a good era for "prefabricated" houses. Overall, you tell far too little about the property. Basically, I am happy to recommend the "prefabricated house expert" Tobias Beuler. And you can look here in my posts with the keywords "Kampa" or "Okal Haus", there you will find some clarifications about timber frame houses from this period.

Or are there alternatives? For you? Are you very restricted to one place of residence? And is this the best location? Or do you have several places in mind? Then I would wait. Surely much more will come onto the market at lower prices in the next few months (especially in the building age category) due to energy costs.

The problem is that we have been searching for 5 years.
Unfortunately, we are not in any club, the municipal council, or anything similar.
Here, almost everything goes under the table. On the usual online portals, there has been nothing for years that is comparable in price and location to the current offer. We are only getting this house because of a former classmate. It is not listed online.
Therefore, nothing can be found within a radius of 10-15 km (we do not want to go further).
If we moved to a "one-horse town" <2000 inhabitants, it would surely look different again.

At least the parents are just around the corner considering the two small children, but it is certainly not the dream house, no...
We have been waiting for 5 years for things to "get better."
They did not - on the contrary.
With today’s knowledge, we would have definitely gone for some offers that were just as poor in quality as the current one.
The houses here were and still are outrageously overpriced, but we do not want to leave here.

Now they say again that it will get better.
We are simply running out of steam... we are just tired...

If the property is already worth 320k, then the house is a bargain. How much additional budget would you have for the refurbishment / renovation?

Prefab house (timber frame) so the question about the building fabric is already advisable.

Ergo. View with a professional.