depending on which bushings and wear parts are needing replaced, you could easily rack up a parts bill of over $200. add in the labor to disassemble and reassemble the clutch assuming the sliding sheave bushing is being replaced and you could easily factor in another $100 for labor. without knowing the whole story and what all parts need replacing or to be replaced in the higher estimate, probably not that far off.
you can find used clutches on the average of $200 and up, but you never really know what your getting so it could be a step backwards.
you can service or install all the parts necessary yourself to make that sled work at its new location except for the sliding sheave bushing. you need special tools and a bit of know how to perform this procedure.
i would get some more info as to what all needs to be done or replaced and if in fact that sheave bushing needs replaced, have the shop fix that for you.
from there you can install the other parts and probably save some cash on parts from discount online parts suppliers loading your own clutch.
if the shop is familiar with this machine and its high altitude requirements, you may be ahead of the game going that route. from there i would suggest using clutching specs from a 2000 or 2001 phazer mtn lite.