Land available but only a condominium?

Would you like to give concrete numbers? Otherwise, I'll stick to my opinion: build anyway.

Do you still remember? They don’t get financing!

Usually, you build what you can afford. A fancy country house of 350 sqm is not even planned by a normal earner (there are exceptions ;) ), for plots you usually take what you get. And when you are in the phase of nest-building, many have to be creative, accept that some things won’t work as planned, rather focus on plan B or surrender. Yes, you don’t need 60 sqm storage space, you don’t need a garage or a carport, you don’t need a two-story house, and so on.

I take this quote as an example:

hip roof etc. is not possible, it has to be a gable roof. currently planned with knee wall, but if the building authority says full story is allowed, it will be a full story.

from that point of view, unfortunately there is no saving potential here.

Leaving out the basement is not an option – because the plot is 300 sqm. and we need storage space–

You are sugarcoating the numbers. There are always two options: you take the more expensive one. A hip roof is more expensive than a gable roof. If you take a gable roof, you generate endless storage space under the roof. As said above: always think about plan B.

Turnkey price

That doesn’t exist either. Very likely, some additional extra services will be added, details are in the construction service description. Usually, flooring and painting are not included.

And here it is in black and white:

we are also planning for another child. from that point of view, the 2500 monthly is simply unrealistic.

That is FACT: You cannot afford the house on this plot. And since building does not get cheaper, you will probably never be able to afford the house on this plot unless your wife/state contributes more to the finances. You can calculate the time when that will be. By the way, _well earning_ is relative. It doesn’t seem so good that it is enough for the bank despite equity through the plot.

How plan B could look like for you is missing information. Basically, however, the hoped inheritance will probably be used for care for the respective person who saved it, so it should not be counted on.

-Time aspect:
For example, you could stay in the apartment for several more years or perhaps it doesn’t even have a spare room for 2 children (one room for two is enough in young years).

-Does it have to be ownership? Why? To put it plainly: if you plan a mega carport at the garage, then maybe the garden is not very important to you?!

-Sell the plot, look for a simpler plot over the years, and then build tailored to your needs.

Regarding your question:

if I find an apartment where I can buy for example 3 or 3.5 rooms for 320-385,000,

I don’t know the area where you can still get affordable living space via a condominium. But it may be that you either accept it as your home and will spend 10/15 or 25 years there or won’t accept it because of the circumstances. Everyone thinks differently. But I advise you the first option, because the huge additional buying costs usually don’t justify buying and selling real estate financially.

That’s why you probably have two realistic options: build now without a basement and garage (and, if you want, put up 2 garden sheds) OR don’t build and live in an apartment forever. Because honestly: why do you need so much storage space? You don’t have that now, nor in a condominium for sure. So go for it now and build your 120m2 without a basement and garage, or the dream of a house might not be big enough. Because all other options are very uncertain and the chance that you’ll build someday is rather low (continued high interest rates/construction prices/inflation with no end in sight). Maybe the building situation will be even worse in a few years? Who knows. Better build now!

Are you still with it? They are not getting any financing!

I actually interpreted that differently. I thought the rate was only "felt" to be too high.
It was written that there is an above-average income. In addition, over 100k saved by age 30, despite having a first child.
Unfortunately, no numbers have been mentioned yet.

Do you have any obligations on the property? You mentioned something about demolition, is it still habitable? If not, will it hold up even if you leave it standing for years (what are the possible maintenance costs for this)?

Regarding inheritance, I think it’s basically okay to have that in the back of your mind. But if possible, I wouldn’t hang my "construction start" planning on it. Either you can convince someone to chip in now (or set up a private loan or something similar) OR it just comes whenever it comes and who knows in what amount then. My grandpa was around 80 when he was in such poor health that we weren’t sure if he’d survive the next winter. He did. Also the next 10+... He’s now 93 and basically every winter is like that now. It could be that he doesn’t wake up tomorrow. But it could also be that he just keeps going like this for another 10 years. In contrast, my grandma was still up the cherry tree with a ladder in the summer and it was over in the winter. The point is simply: you just can’t plan for this. Is your "temporary solution" acceptable for you for such a long time or is it actually foreseeable that you’d prefer to be out again in 2 years?

Then the money was just thrown at your feet. Probably by the employer. It is an illusion that you earned it because you deliver such good performance or are so great.

Also an interesting interpretation. Oh man ...

125k € equity is already great at 30. And without subsidies from family, even higher to be valued.

I would simply plan the whole place at 135 sqm of living space and that’s it.

Someone is probably jealous of 125k. It's already embarrassing if you need that. Everyone is free to save just as diligently here. And reducing the living area is also my answer to your problem. Then just 50m2 in the basement, on the ground floor, and on the upper floor. 100 m2 living area and 50 m2 basement area is still better than not building. You can get that for 400k even without a garage. If you lower your expectations, you can build now. It's bitter and annoying that maybe a year ago you could have gotten about 10m2 more per floor in total. But that's the only way for you to reduce costs.