Price difference between ground slab and basement. Can it be estimated?

Is a house "worth it"? Is 128 m² worth it, when 127 m² would do just as well?

Who has, can ... If I could, I would have a basement.

Whoever has, can ... If I could, I would have a basement.

If you needed one, yes. But with a flat plot, just putting a hall under the house for an underground connection room doesn't make sense to me. Model train worlds have become quite unfashionable, as have perfectly equipped workbenches, when most of the time you'd rather call a craftsman. A basement can not only be a blessing, but often serves as a decades-long storage space for junk. Then better to cellar only 127 sqm

If you needed one, yes.

What does "need" mean? I would have uses: wine cellar, workbench, sauna cabin, whirlpool, guest room, storage place for garden produce*, recording studio/hobby room, storage for Christmas tree baubles, money vault, .............

Yes, all that could also be done above ground, but then the built-up area grows and the neighbor immediately sees how big my palace is.

* I don’t even know if modern cellars within the thermal envelope of modern houses are as suitable for that as older cellars were.

My cellar is constantly 21 degrees. I can't get it any cooler.

My basement is consistently 21 degrees. I can't get it any cooler.

If it is not heated, then something is probably wrong. Or where is the heat coming from?

It is well insulated and the [Fernwärmeleitung] is inside.