Depends on if it's a first gen car - N1 or an N2.
I just had my clutch replaced by the "barn man" and I doubt if there is a more reasonable guy out there. When you do the clutch it's not just the clutch, no really good mechanic would recommend resurfacing the flywheel - so most cases - you'll need one and then there's the master and slave - usually replaced if it's old. For mine the total job - clutch, flywheel, master and slave cylinder as $2400 - deal!
If the car is a later model N2 then you'll be looking at around 4k - the dual mass flywheel cannot be resurfaced and it's all more expensive stuff - you may not need a master or slave - depending, but it's a case by case basis and be ready for a pretty big hit. It's a big issue no matter what but if they feel funny it probably has some issues or if it slips certainly. There is no mileage really as it is in many cases owner operation that dictates replacement. If driven correctly - you can get a lot of miles out of them - around 75k miles - but that can be cut in half easily by someone that has no clue and rides em on a hill - you just never know.
Hope that helps.
