The cost of CO2 heat pumps depends on what features are ordered with unit.....communication package with remote capability, optimized heat exchanger for fluid temperatures etc....these units are UL rated, performance tested under lab conditions and certified/insured for US market. Getting a CO2 heat pump UL rated and insured for US market is VERY expensive due to pressure testing and other requirements, so you cannot compare this unit to a "garage built" system that anyone can throw together and give it some crazy COP with no real performance data. With that said, units are in the $650 to $850 US per kW list price. Discounts for wholesale, multiple unit orders etc... are lower.