How much will the ARC Tunnel cost if construction is delayed?

In 1968 the MTA estimated that the original 3rd Ave LIRR terminal and extension of tracks from 63rd Street would have cost $195M or $1.2B inflated to 2009 dollars.  Today this project is costing us roughly six times as much.  Imagine how much the ARC tunnel project will cost New Jersey if the project is delayed.