I think shops usually charge like $80 or something when you buy it there but its not that hard. I say do it yourself because its worth the journey -All you need is a jack, a ratchet set and $50 to rent the compressor (which you'll get back).
Alls I gotta say is be the f_ck carefull and rap the spring with a towel when you unscrew the the hat from the pisten rod.
here. . .

Thanks to agent87