Is a penthouse feasible for 350,000€?

I notice that the tone here in the forum was friendlier a few years ago. It's a pity that newcomers with differing information are dismissed so curtly.

I like to be a realist, and I personally did not find myself too bold. What is the use of beating around the bush and sugarcoating things? I am used to ZDF and these help me the most. Own effort is often massively overestimated financially and also "in action" itself. I see that as a huge problem.

I notice that the tone here in the forum was friendlier a few years ago. It's a pity that newcomers with differing information are dismissed so harshly.

I can neither detect a bad tone nor can I remember it being different before. What kind of rose-colored cloud is this where people are no longer allowed to openly state the facts? Is it better to learn the hard way just so that everyone feels pampered? I find it much nicer not to let others run into ruin. You can also use clear, definite words for that. In any case, I have not read any personal insults or the like.

Since so many people here have a house on a slope and can apparently provide experience reports:

How big is your house on a slope?
What did it cost?
How much work did you contribute yourself?
Garage yes or no?

By the way, this is what I imagine experience reports to be and not just: no, that doesn’t work

We built a house on a slope in 2023/2024 in a rural area in southern Bavaria. 160 sqm + no basement but two enclosed terraces (expensive matter) and a large single garage integrated into the house (masonry).
All in (including photovoltaics, kitchen, etc.) with garden (not to be underestimated on a sloping plot), etc., we are at around EUR 640,000. This whole thing with a lot of own work. For example, we built the garden wall ourselves with acquaintances (and an excavator) – just the materials for that cost about EUR 10,000. A contractor would have charged EUR 20,000-25,000 for that.
Admittedly, our house is top equipped and I once calculated what would have been possible with cheap-o equipment. I wouldn’t have come under EUR 400,000.
I’d say, if you make extreme cuts (standard tiles, standard bathroom [preferably only one bathroom], no ventilation, no photovoltaics, cheap kitchen, low ceiling height, as small plastic windows as possible, plastic floors, mechanical shutters, no integrated spots, etc.) and do a lot of your own work, you might somehow get to around EUR 400,000. But then you have a very simply equipped house. You have to be able to live with that (those who buy cheap often buy twice).
In addition, you have to take into account that prices have already risen significantly again since 2023. You will never get under EUR 400,000 at that size with a basement. An acquaintance of mine was similarly naive about building a house. They wanted to build a wooden house for EUR 400,000 (without basement with 200 sqm). The offer for the shell with roof and exterior plaster was already EUR 450,000. They then planned financing for EUR 600,000. I already told her before that this would never work. Now she has found out that just the heating for the house (without ventilation) is about EUR 70,000. The house will in the end cost EUR 800,000-900,000 with all additional costs (e.g. land development).

What is now massively underestimated regarding self-performed work is that the material prices for very small quantities by far do not correspond to the prices included in the calculations of the craftsmen. We saw this with our sanitary installations. When we heard the prices before discount from our craftsman in the showroom, we almost fell off our chairs. When the craftsman’s offer including installation and warranty was presented, we were really positively surprised.

There is another serious issue with self-performance: if faulty, incorrect, or insufficient material is delivered, you often have to chase the complaint for ages. We experienced this in the outdoor areas. The granite curbstones were defective, the L-stones had lime deposits, the stainless steel light well covers rusted after 5 weeks, the hygiene shower in the WC was already leaking twice (the only part in the bathroom that we procured ourselves), etc. Always having to handle all complaints yourself costs not only a lot of nerves but also time. So if you do 80% of the house yourself, you have to deal with this factor X yourself. You don’t get to hear much about that with a construction company. It feels like it doesn’t matter what you buy; for 2-3 years now, the quality delivered has not been the same. We hardly had any piece of furniture (sofa, corner bench, wardrobe, coat rack, etc.) that we didn’t have to complain about due to defects/issues.

When we heard the prices before the discount from our craftsman at the exhibition, we almost fell off our chairs. When the craftsman's offer then arrived including installation and warranty, we were really positively surprised.

The prices in the wholesaler's sanitary exhibition are completely exaggerated moon prices. Take a look in a hardware store, then you'll see what the stuff really costs. And for the so-called branded goods, a look on the internet is enough.