Your math is close but I would not include the assembly cost of the Mk disti board, just the number of BL controllers and the appropriate distribution board. In either case you also need to include the cost of the same number of PWM ESCs that will be used with the WKM to make it a fair comparison. Basing it on something like the Maytechs I'm using on my CS6, that adds another $180 to the cost of a WKM setup, actually closer to $200 if you add in the cost of connectors, heatshrink, etc. Still the PWM ESCs are a lot less expensive than MK BL 2.0s and a whole lot easier to replace.
I did this same exercise quite a while ago when the WKM was first released and I figured the actual expense either way for a hex is close with the WKM having a bit of an edge in the cost department. If you consider functionality included for free in the MK software then perhaps the Mk could be considered the better deal. Even throwing in waypoints on the WKM side it still isn't as lopsided as you might think, yes the component pieces are a bit more expensive for WKM until you factor in the fact there is no distance limitation like there is with MK. To get the closest thing MK has to a long range waypoint capability, add another approximately $2000 US for the 1000 meter commercial license for the Navi board.
At least for a standard hex(a) I wouldn't necessarily give an advantage to MK. Having owned two Mk based hexa for a couple years now I'm not convinced either of them would continue flying on loss of a motor any more than my WKM CS6 did when a motor quit in flight and it became a bucket of bricks on New Years day. If it weren't winter with snow on the ground I'd put my old Y6 frame back together and test it with both Mk and WKM to see if it would fly with a motor out, I know it would with Mk electronics, I've yet to see it proven with WKM.
I haven't found Mk to be any better in windy conditons than WKM is. In any reasonable amount of wind that I would consider within range for acceptable video work I can get as good and possibly better video with the WKM/CS6 than I have with either of my MK hexa. If run through stabilization on the backend neither one is a clear winner, on raw video I'd have to give the advantage to the CS6 but that may be more a function of the frame and camera gimbal mounting system more than anything that can be attributed to the flight controller.
When it comes to altitude hold and GPS accuracy, the WKM wins, hands down. I own and fly both Mk and WKM and there is no comparison, the WKM works much better than MK to keep the airframe level, at the same altitude, and I have watched both of the WKM I own do an RTH and autoland winding up within a meter of where it took off from. No way MK can even come close to the WKM's degree of accuracy in any of those areas. And keep in mind it took MK years to get to the level of capability it has now, WKM has been available to the general public for just about 6 months now and all of the features have worked since day 1. I can only imagine where it might be in another year if it's been this good out of the box.
Ken
Nuremberg is going to be VERY exciting..