Hello nordanney, so the costs for the heat pump + drilling were about 30,000 euros - that's definitely a hefty amount :(
It's a hefty amount, that's true. But it's also a huge block of a house that needs to be heated. If the house were significantly smaller (and the family size too ;)), the price would also be much lower. Smaller heat pump, only one drilling instead of two, less underfloor heating, no charging storage, etc.
The price is actually quite reasonable. We had offers that were significantly more expensive. Our heating engineer can offer great prices because he supplies almost all the houses in our building area (certainly more than 50 installations in the last three years). There is no gas here and therefore no big alternatives.