back up camera:
attached to plate
bought at tsikot.com shop
HU has a cable output for the camera included
2,500.00
free installation

headrest monitors:
7,500.00
carland
HU has no cable for video out put
bought cable at carland at 1,200.00
free installation

did you try opening the HU? when mine was opened it has a cable for back up camera but none for the headrest.