Estimated total costs for a semi-detached house

Then ask the couple what other costs they had. That is a possibility and a reliable source :)

That is of course a simple way! ;)

Connection Telekom, construction power / construction water / portable toilet / waste / etc. No idea what is stated in the construction service description, but there are many additional items that you simply have to plan for under miscellaneous. Are 5000 € really enough for floor and wall materials? How about financing costs, double rent, etc.? Is the plot fully developed or will there be additional development costs afterwards?

I have included connections, the numbers I received directly from the suppliers. The builder takes care of construction electricity and water, I asked him directly and he said they would cover all incidental costs incurred during construction. The floor is completely tiled except for the bedrooms, so I think we could manage with €5000.

Double rent is not included here. Development costs will be added later, according to the municipality in a few years. At the moment, they would be just under €5000. Sewer works etc. are already settled.

I have included the connections, the numbers I got directly from the suppliers. The construction electricity and water are covered by the developer, I asked him directly and he said they would cover all incidental costs incurred during construction.

Get that in writing, exactly what incidental costs he covers! What is not on the list, he does not cover either.

The floor is tiled everywhere except the bedrooms, so I think we could manage with €5000.

What kind of tiles do you want? Please remember that you cannot just calculate the pure tile price, but also the adhesive and the installation.