What is a realistic construction cost / single-family house

Hello everyone,
first of all, many thanks to everyone who takes the trouble to share their experiences here and thus help with the planning.

A brief introduction about us:
Me:
25 years old, civil engineer / civil engineering
My fiancé:
27 years old, lawyer

Income:
Me: €4100 net
Him: €5400 net

Planned tax classes:
IV/IV

Disposable income after deducting all fixed costs as well as the average of other living expenses:
€5500

Equity:
Used for the land purchase

Land plot:
1100 m2
Purchase price €220,000
Lower Bavaria

Planned house:
- 170 m2
- Basement
- Kfw 40+
- Basic KNX system
- Double garage
- Brick facade

Now to the actual problem:
We completely lack a feeling for the necessary construction sum for this project. One would think that as a civil engineer I would have a certain home advantage, but since I work in transportation infrastructure construction, I am absolutely blind regarding the 300/400 cost groups.

Nevertheless—everyone has a pain threshold:
We would prefer not to spend more than €600,000 on the 200-500 groups.
That would put us at just under €3500/m2 of living space maximum.

I have actually calculated with an amount around €2500/m2 as a "desired" cost.

I know that breaking it down to €/m2 prices is difficult, but at least it gives us a rough direction for the upcoming discussions with Gus/prefabricated house manufacturers.

I would therefore be very interested to hear which m2/€ prices you consider realistic for our construction project.

Depends
With 2,500 euros it works, 3,500 euros might also not be enough

Gable roof or hip roof
Gallery yes/no
Corners and bay windows or rectangle
Laminate or marble
Bauhaus not just cubus
etc

I would take 2,000 euros per sqm
+ basement
+ KNX
+ garage
+ photovoltaic with storage
+ clinker
+ possibly high-end fittings
+ ancillary building costs

Definitely keep an eye on the earthworks including disposal and slope stabilization

A bit off-topic:

Are you sure you are not confusing gross and net? You just finished your studies and earn a good ~100k?
I've heard a lot, but this is an absolute new high score

Me:
25 years old, civil engineer / underground construction
My fiancé:
27 years old, lawyer

Income:
Me: €4100 net
Him: €5400 net

If the numbers are correct, you can basically afford whatever you want. Currently, interest rates are so low that a 100% financing with the income still offers reasonable conditions.

I would estimate about €600k-620k for the house

A bit off-topic:

Are you sure you’re not confusing gross and net? You just finished your studies and earn a good ~100k?
I’ve heard a lot, but this is an absolute new high score

Me:
25 years old, civil engineer / civil engineering
My fiancé:
27 years old, lawyer

Income:
Me: 4100€ net
Him: 5400€ net

If the numbers are correct, you can basically afford whatever you want. Currently, interest rates are so low that a 100% financing with that income still offers reasonable conditions.

I would estimate about 600k-620k for the house

Yes, I am sure that I have not confused gross with net.
In fact, it is not too far above the industry average.
I work with a master’s degree at an Austrian corporation that cheerfully places its signs on German highways.
My fiancé works at a large law firm in M.

That’s why we wanted to set the budget at 600,000€, since I know our lifestyle ... a rate that is too high would restrict us too much.

A civil engineer who earns 4,100 net at 25 years old, so almost 100,000 gross, I have never encountered either. Crazy.

Apparently our income is more interesting than our construction-specific question. But for the gentlemen who absolutely want more detailed information about my payslip: I earn just under €88,000 gross per year. That results in a net of around €4,100 - according to my personal tax situation. It makes a big difference - especially as a construction engineer - whether the degree was obtained at a [FH] or [TU] and where and in which field one works. I have completed both my Bachelor's and Master's at the [TUM] - so I don't have to take the contemptuous "construction!!! engineer" as a better foreman to heart. Should I now send the interested parties the payslips of the last 3 months? Then please request via PN - but I will then charge a €20 fee to improve my miserable salary as a construction!!! engineer. Aside from any polemics, I am still grateful for answers to my question.