
Agreed. A smaller sensor will always cost less than an bigger sensor assuming comparable pixel densities. No issue there. But take this example, I would guess the raw cost of the APS sensor would be something like $50, and say the FF sensor is $100. 2X the cost for the sensor, but only $50 additional for the camera. I would guess the other electronics of the Rebel and 6D would actually be the same given the feature set. The Rebel costs $800 and the 6D cost $2000. What's with the extra $1200 cost adder?
-Larger mirror
-Larger shutter
-Larger pentaprism
-AF sensors optimized for the sub mirror assembly in a FF body
Of course, Canon could raid the parts bin a bit for the shutter, mirror, pentaprism etc, and those things probubly arent THAT expensive...
You're likely paying for the R&D, Or you're paying for Canon's tooling...
It could also be that Canon expects to sell say... 250,000 Rebels along the life of the product, which in this case is expected to be 12 months, and the sensor, AF module, and other things are carrying over to the next model anyways most likely and parts are shared with the 70D and possibly a 7D Mark II, Canon may expect to only sell 100,000 6Ds and most of the things in the 6D are not shared with other cameras, when the 6D gets replace (I'm guessing a 2-3 year life cycle on this body) its unlikely much of it can be reused in a subsequent model...