the trouble with cheep screens is that they tend to be thicker, so installing them in the sunvisors looks crap unless you are confident enough to remove their caseing and just mount the actual screen. also be carful that the screens you get are PAL or NTSC/PAL switchable (standerd in the states is NTSC) otherwise the xbox wont work on them. to get mine fitted (just the screens, not the PS2) cost me about £650, and they are no thicker than standerd sunvisors and dont need clips to stay up. not cheep but they look proffesional and you wouldnt know from the outside that they were there.
Luke