According to Canon's website, the 90d (not sub-$1000, but maybe discounted in near future?) supports the following HDMI output options. I would assume that the 4k would come out as 10-bit, 4:2:2.
But under HDMI Resolution, not sure if Auto is 4k. Otherwise, it may only come out as 1080p. Anyone know about this??
Auto / 1080p
HDMI output for movie footage
Supported (HDMI information display)
HDMI HDR output
Color sampling method
Uncompressed YCbCr 4:2:2, 8-bit
Uncompressed YCbCr 4:2:2, 10-bit
Uncompressed RGB, 8-bit
BT.709, BT.601, BT.2020
(look under specs>video shooting>hdmi outpout)