It´s a good calculation...
I also have a DraganFly IV and I´m very pleased with it. The only odd for me is that the blades are sooooooo easy to break up. So I´m make my own.
The steady copter could be much more expensive to fix than the DF PRO (I think).
Anyway, I think the guys at the DFI need some competition to make them decrese the price.
The thing you said about the GPS and the authonomy are very cool caracteristics.
DFI have an electric sailplane called Predator the (about 750 dollars) that can be (adding 6000 !!!!!) for the GPS.