The 05 should be remote start ready, meaning you buy the dealer kit and then they enable your bcm for remote starting, program the remotes etc.
It's just a little reciever they swap with your current keyless one and new remotes but with the kit comes a code or something they use with your vin so they can download a new calibration to the bcm.
As for the price im guessing its around 200 but wouldnt hurt to check.