You mean the 3-pronged type?? I have a fairly healthy suspision that if you go to Renault they will supply you with a complete 3-pronged assembly that you have to put back on yourself. I am of course assuming here it is the n/s one as the o/s side one is fixed and attached by the stub axle.
If n/s then you have to take it off to replace the rubber gaiter, and just needs pulling off (with hammer) and new one sliding back on.
Dont know about cost, sorry.