It depends on the type & make of the supercharger as well as the performance stage. You have 3 levels where more performance options are added. They range from 10-20k unless you do it all yourself. Check out this link:
https://nationalspeedinc.com/packages/
Even has your name on the rear quarter panel of the GT 350! Super cool! Hopefully, I can have something nice and super charged in my garage when I am older instead of a boring electric or flying Jetson mobile!