NCP cars are illegal to keep and drive and cannot be regularized unless you have the import documents, which are not available for cars in nothern areas, fata and balochistan.
At times the govt announces a date for regularization of such cars but that is a rare event and only for local residents.
You can get documents prepared for different rates from mere 10k to 100k but the fact is you might get computerized plates yet your car file will not have any custom clearing and import documents