Do you have a building obligation on the property?
If not, then I would buy the property now, save for a few more years, then the inheritance will also come closer, educate myself comfortably and without time pressure in the meantime, and then embark on the house-building adventure.
When we started, we also initially flirted with offers of houses that we found quite acceptable. They would have gone for 300,000 euros in the catalog. In reality, you end up somewhere completely different.
12 sockets in the living room? I once calculated, we have 14 and in some places it's tight; and we partly have sockets with an extra USB slot, so we don't need a socket to charge our tablets/phones. You underestimate that! The standard construction service descriptions ALWAYS have too few sockets, everyone should keep an eye on that (and I can really recommend that to everyone!) and that quickly gets quite expensive.
Very few people today still want a 90x90 shower tray but rather a walk-in shower – but that's certainly not included in the normal construction service description -> costs extra!
What heating concept? Etc. etc. etc.
All things you don't worry about initially but that are important.
So if you have the leeway to postpone the construction, then do it!
That's exactly how it is. Please get rid of this price right away so you can plan realistically.
The standard in the construction and service description is really so "standard" that no one wants it – at least not in many things. If you want to live in this house, it is actually comparable to a Fiat Panda in standard equipment – there is really NOTHING included... And believe me, you have to "upgrade" your house – otherwise you simply can't feel comfortable. Prefabricated houses sometimes have an even lower standard than regional solid builders (that's because they want to lure you with cheap prices, but the construction and service description is really a complete disaster).
Just so you get a feeling for all the things you can/must/should/want to upgrade:
- Sanitary equipment → if you only want something reasonably good there (you're really not even in the mid-range segment yet), you'll easily be 5,000€ more away.
- Interior stairs → you can burn money there :D – so you can easily get an additional cost of 3,000€.
- Interior doors → The standard will blow you away :D
- Floor coverings → The prices are sometimes so low in the construction and service descriptions that no one would ever find a tile they actually want to install :D
- Electrical planning → interior hot spots, exterior lighting, sockets, additional switches etc... never enough in the construction and service description
- Front door → easily 1,000-2,000€
- Windows → if you don't want the cheapest white plastic windows but maybe colored (not foil-wrapped but with aluminum shells or similar) you are quickly 5,000€ away
- Exterior house painting with color → 1,000€
- Special equipment like fireplace, garage, ventilation system, photovoltaics, and so on... You'll be several tens of thousands of euros away if you consider these
- "Little things" like burglary protection for windows, electric shutters, heating filling block, changes to the floor plan, flush-mounted boxes, satellite system, window sills, ...
These are just things that came to mind spontaneously, and we didn't have to think about it as much as you do because our standard with the regional solid builder is already relatively high, which also means a higher initial offer price.
These are just the sampling upgrades... You will see that many costs that you haven't even listed in your incidental construction costs won't be offered by the general contractor and are therefore construction-side services... You will then see this in the construction and service description.