I just got a quote from a Porsche dealer on this. The parts are around 950 bucks and installed, a new PDK clutch will cost 1900 dollars. This doesn't seem so bad given it's about or less than the cost of a new clutch on a manual car and you gotta figure a PDK clutch will outlast a conventional one given the computer does the shifting. It'll be interesting to see whether it outlasts a manual clutch in practise.