Depends on what clutch u are going for. I just got my clutch done on my IS300 for ~$1200 with a ACT Heavy duty street kit. That includes machining the flywheel, a new crank seal, and 3 bottles of redline tranny oil. And an engine oil change too. lolz.
ACT part number is TS5-HDSS, should help you find it easier. If you decide to get this. OEM replacement is an Exedy kit, which is about $100 cheaper than this one.
Thats the flywheel before machining.
PM me for more info! Ill help a fellow 5spd IS300 owner. =)