Comment by scottLobster

Yeah, if you have a bare minimum of 30k burning a hole in your pocket and enough open land to drill the well with the correct geology, and the larger your house the bigger/more wells you need as you're drawing from the Earth's relatively constant temperature. So the only way to get more heat is to get more surface area for the coolant.

Some people on reddit are reporting quotes of 125k for larger (>3000 sq ft) houses.

As someone who lives in a 4-season environment that can get down into the single digits F on occasion in the winter (forecast to be there for a couple of days next week), and has an air-source heat pump, I just suck it up and eat the $400-$500/month heating costs for the auxiliary (electric resistive) heat in Dec/Jan/Feb. If someone gifts me a ground-sourced heat pump I'll gladly accept, but I've got kids to raise so setting aside money for one is a long way off.