yeah it only comes as a complete gearknob, however as you know, you can simply pop the silver bits off and swap meaning you dont need to remove the old gearknob itself which saves a bit of hassle.
I paid 25quid from renault for a new complete gearknob, however they dont make the 1 that was originally fitted to 04 dynamiques anymore so I ended up with 1 from a campus sport, which looks very similar to the 1 in your photo, and it feels different, the silver insert that is, my old one was a smooth shiney effect that wore away to the plain black plastic underneath, this new 1 feels as though it wont wear away quite as badly/quickly.