Not sure if you will be able to register the car in Islamabad if you are not a resident. Check around for a way around this. My ID card has permanent residence of Islamabad but having just the present address as Islamabad may also work but not sure.
Anyhow, for non filer registration cost that you will pay at the ETO office in Islamabad is:
Registration fee 52900
Motor Vehicle tax: 384
Income tax: 15000
Smart card price:1500
Number plate fee: 1300
Total: 71084
Note: Take a lady along with you. Things go faster.