First draft single-family house 160m2 - Please provide feedback

Actually belongs in another subforum, but I would like to use the topic here.. Our construction company currently has a "special promotion" and offers the KFW 55 standard with a geothermal heat pump for an additional charge of 16,400€. Deep drilling would cost another 2,800€. Currently, we are planning a gas condensing boiler + solar. If you subtract the subsidies (5,000 repayment grant, 4,000 Bafa, 2,000 unused gas connection), it actually sounds interesting. Have I overlooked anything?

We were told that a deep drilling should cost around 10,000 euros.

Best regards
Sabine

I have also heard of prices between €8,000 and €10,000. But we have received the price from our construction company in writing as a fixed price.

And by fixed price, does he also mean that he will cover any potential difficulties with the drilling? So the required drilling is absolutely guaranteed to you? Sounds fair...

Perhaps the external inspection or accompaniment by an expert still needs to be paid for by you? Maybe discuss with the BU

Best regards in brief