For reference, over the past year i've acquired 3 sets (Robot Controller, OI, and matched radios). I payed ~$400 for one set that was Stamp based + two 884s + two joysticks and about $120 each for the other two which were both Pic based. I've see them listed for much higher, but did not pay attention to whether they sold or not.
P.S. They've held up well for me so far in my combot.
But they are bulky.