Well, that's also correct. Not just the clockspring though. You will need the clockspring, the actual radio controls, and the ignition wiring that attaches to the clockspring. You can actually attach the radio control to your existing steering wheel. As far as the labor, It's easier to just replace the column. But if you are buying the parts online, yes it makes more sense from a shipping standpoint to ship only the clockspring and wiring.
On a 03-06, I believe all you need is the clockspring and the steering wheel with buttons.