How do you come to the conclusion that these are discount prices? The provider offers 130K for a normal house of 100sqm. For every enlargement, it costs us 1000€ per sqm. That is normal for a standard price, right?
As far as I remember, a general benchmark of 1,500 euros per sqm is assumed for "standard equipment." For lower standard, I have the value of 1,350 - 1,400 euros in mind. I don't remember this whole thread anymore – was this supposed to be a shell construction for you? Then I can imagine 1,300 euros since you would still do many interior finishing trades by yourself. If not, to my knowledge, 1,300 euros/sqm would be rather very cheap. Although – an enlargement is actually somewhat cheaper (whether 1,000 euros is enough there, I don't know).
By the way, you once wrote that you were considering Heinz von Heiden (I hope it was you). There is currently a thread running ( ) stating that Heinz von Heiden combines a heat pump with radiators (standard). As far as I know, underfloor heating makes the most sense with a heat pump.