Chief, I got one challan by the motorway police for over-speeding, near Multan. It was Rs. 750, I was slightly above the speed-limit, not much. I was travelling at 111 km/h on a road where the speed limit was 100 km/h. Other than that, no other challans.
Very roughly keep aside around Rs. 700 for toll taxes up till Lahore (generally toll tax is Rs. 30 per ticket, although Karachi and Hyderabad toll plaza's charge Rs. 40). If you take the Lahore Islamabad M2 motorway, toll plaza from Ravi (Lahore) toll until Islamabad is around Rs. 400 (from what I can remember). GT road will be much cheaper, but will take more time to travel.
Sab say zyaada lutt maar was at Bhurban toll plaza, which is less than 100m from PC, and they charge Rs. 200!