to give you some idea mate i just put a carbon button clutch kit in my SII 33, the kit alone cost me just under 500 at trade price.
i did it after hours at work, first skyline box ive taken out. It took me an hour or so to get the box out, a further 10 minutes to get the pressure plate, clutch plate and fly wheel off. Being there is no spigott bearing, only a bush i didnt need to inspect it.
had the flywheel machined by AMMS in brisbane for i think $50.
refitted flywheel and new clutch kit and aligned clutch took about 20 mins.
refitted gear box.. well this took a little longer as the section in the bell housing where your starter bolts to hits the tunnel so you need to spin the box a bit. but still only took about another hour and half.
id also advise changing gearbox oil as they can commonly break the detents in the box and if this has happened can lead to more damage so by changing the oil you can check this as the drian plug is magnetic.
thats just an idea.. as for pricing id be thinking for standard clutch around 800ish. but if you have a h/duty clutch already i wouldnt advise going back to standard cause you will be disapointed.
just my experience hope it helps if ya needa know anything just ask mate