Ok, I understand.
Since I don't know the region: What are the developer prices for comparable turnkey construction with you? ~400k per semi-detached house would be a dream price for buyers elsewhere, and for you, quite a bit would stick, if you just design, build, and sell instead of renting. Although it does not correspond to the nice motivation to provide (still) not yet able-to-buy young families with a good living situation, it shows in my opinion that the location might not be so dramatic that it directly needs a memorial (instead of living space)!
Good luck further with the project and conversations!
That is a good question. I think I can roughly approximate it.
Semi-detached house,
solid construction with two-layer sand-lime brick and clinker, concrete ceiling KFW55 standard
finished ceiling height 2.80 m
decent windows with shutters
air-to-water heat pump + ventilation system
I estimate 320-350k
+ ancillary construction costs (interest, connections, static calculations, etc. etc.) certainly 35k
+ plot (developed) 25k
+ fitted kitchen, driveway, carport, terrace + roofing, garden shed, fence + setting curbs, roll-out lawn
- if done by others, about 50-65k? That adds up
Finished around 450k turnkey house + garden etc. +/- 10%
That would mean, with 20 years fixed at 2.5% interest, 2.5% repayment, 50k equity, a payment of 1650 per month.
Whether someone then pays 1300 rent there is, in my opinion, daring.
Whether the 20-year-old, used 150m2 houses here, which are currently sold for 450-500k, are really worth that price, I do not know either.
There, in addition to the purchase price, come the high energy costs, property tax, etc.!
With renovation measures like a new bathroom, new kitchen + incidentals, you quickly end up at 600k.