I've only sold a handful, but this is my experience.
Expensive, I'd say yes. Depends on what the customer thinks, but it isn't inexpensive. I sell the system for about $2300, but you need a licensed HVAC installer to actually run pipe and install it (another couple $$$?) The last one we did was about $2700.
Does it work? Absolutely. It's actually really awesome, but cost keeps me from putting it on my own tub, as I seldom use it cold... I mean I never do, and don't really have a problem with it overheating. Now if I was in death valley... I probably would get it.