alt Hacker NewsI paid about EUR 4500 for a 114 meter drill hole including installation of brine (ethanol in my case actually) and removal of spoils. My 8kW heat+water pump was about EUR 7000.
I can spec out a gas burner for about EUR 4000 and a central AC for EUR 5000, but I bet the efficiency of the ground source heater would quickly trump the cost of buying gas regularly.
That's insanely cheap compared to what we can get around here. Most installs I've heard of from people in the US are in the $20-50,000 range, depending on the size of their home and number of wells needed.