Clutch kit is about 60-70 quid, and it should be a 2 hour job for a half decent mechanic. At least thats how long it took me and my mate to do mine.
It's worth asking the garage if they actually take the engine/gearbox/both out to do it though, as some places do and you dont need to. We just dropped the driveshafts out of the hubs, unbolted the 'box from the engine and dropped it down on its mountings. Awkward c*** of a job mind!