a third party one costs around $10-20 (check the mass sales section).
My cheapo china brand one bought in 2008 works on 400D and 5DII (and supposedly a host of other cameras too - Nikon, Olympus, Sony)
forgot to add that this is infra-red one so while you are not constrained by cable length, you need line of sight to the sensor on the camera (front right of the camera near the grip)
RF 602 is quite a good choice though I have no idea the price now.
I'm using 602 with 40D. It can be used as a remote as well as a wireless flash trigger!
RF 602 is quite a good choice though I have no idea the price now.
I'm using 602 with 40D. It can be used as a remote as well as a wireless flash trigger!