Keep in mind the Sulon Cortex (sulon technologies .com, sorry I can't post links), a very similar idea, is going for $500 with a "high-end CPU and GPU" and "special algorithms for understanding the world around you"
HoloLens seems be this with the light thing instead of a display, plus the spatial headphones and the "HPU" replacing "special algorithms." Microsoft should have better relations with hardware manufacturers though, and I'd assume is willing to sell near- or at-cost, at least to developers to get new apps to work with it.
I'm crossing my fingers for a $500 price too, but looking at the Cortex I can't imagine it being much more than $1000