Purchase opportunity for a "too small" single-family house at a "too high" price 120 sqm / 550K

How certain are the 150k for the renovation? Is that your budget or is there already a cost estimate for it? I assume probably not the heating itself and the roof, but how is the latter insulated? What do you want to do energetically and what about electrical and water? Which region? The house doesn't sound very cheap, so I suspect new bathrooms will also be quite costly (and kitchen?)

You are downsizing and initially living on a construction site for a proud price just to live in a good location. What is the good location? Best neighborhood in the city where Professor von Pups and Count Highnose live? I would think twice

It's like always in life: whether THIS price is worth it to YOU, you have to decide for yourselves. Personally, I see too many compromises in the layout here. Just the staircase alone is a no-go by today's standards and hardly can be changed. Besides that, 150K does not necessarily seem like a lot for a really extensive renovation (for such an old house). On the other hand, the location simply can't be changed, so a great new house somewhere else wouldn't help you much either.

We also renovated an old house and slightly downsized in the process, similar to what you are planning, even a bit less space. For us, the lack of a garden was also one of the main factors.

But: that's why we moved to the countryside and now have just under 2,000 sqm of land.
Are you aware that 300 sqm doesn't bring much gain in the garden area?

Sometimes you end up with both disadvantages (price/size) from a compromise (location/green)...

Unfortunately, information about the rent to be paid at the current time is missing. An old house remains an old house. At the purchase price, I would hire an architect to break down the renovation costs. We renovated a house from 1958 (standard, no luxury) and did not come close with 150,000 euros, and that was long before Corona and the extremely increased material prices.

I would not consider a 30-year-old renovation; you might as well start from scratch. But one thing is also a fact: with your net income, you already belong to the well-off, and it would be doable.

If you feel comfortable in the property in the long term with the thought of having paid 700,000 euros for it, you can do it.

At these prices, in the property bubble I see, I wouldn’t do it.