Also, it depends on what you want to do. I THINK that the 2.4gHz stuff is allowed to control airborne vehicles but if you go with a cheaper non-digital transmitter you may have to check the frequencies so as not to run afoul of the FCC.
Also, Im not sure how the VEX controller works but I dont think it has a failsafe on each channel. If you are doing anything large you will probably WANT some sort of failsafe in place.
Camera wise a quick bit of googling showed up
http://www.sparkfun.com/commerce/pro...oducts_id=9189 as an option.
Here are some 4 channel receivers
http://www.robotmarketplace.com/prod...4_channel.html
Here is a 6 channel digital one
http://www.robotmarketplace.com/prod...-SPM66001.html
Just ideas of places to look. Hope this helps.