To build a #1 resto mod the costs can easily go north of $100K. It depends on what chassis, drivetrain, brakes, etc. is used. I've seen the rolling chassis with drivetrain come in at around $40K with an LS3/Tremec 5 speed in it. If you put an LS7 or LS9 and a 6 speed in the price tag is even higher. It also depends on what is done on the interior side. At auction these can bring in the $120K to $140K for a really nice one.
Hope that helps,