How in the world do you end up with $300 per controller? You expect the Vitality Sensor to cost $200?
I doubt the Vitality Sensor itself even counts. I believe it'll replace the nunchuck altogether, you probably won't need more than one.
Lastly, I don't know why people are crying over this. Are Sony / MS' motion solutions so much better, now? Why don't we wait and see the software before passing judgement.