ill take a stab at it, this should be fun.
first off, expensive glass… you get what you pay for. Some glass cost more than the camera. that’s why there was a shootout with the
iphone 6 with a $100,000 lens and it looked comparable to some better cameras.
most cheap camcorders can record 8 bit or even 10 bit, but that is still h.264 or even prores. RAW(12, 16 bit) is not just playing back at RAW speed, it is full debayering, denoising, color processing and compressing a huge digital stream into RAW(a compressed format) in realtime. yes, you read that right, its basically a super computer in a small box.
for example: final compressed codec size. each larger size is geometrically more cpu intensive
The GH4 data rate is 100 Mbps.
Prores 422 4k 503 Mbps
Sony F5 1 Gb/s
Blackmagic 4k 1.4 Gb/s
if you can do all this for $1,000, good luck!
btw, even the coming soon GH5 with internal 4:2:2 10 bit will be $2,000.