For spare parts of Nissan Wingroad and AD Van, u can get the info regarding availability and price of spares from
Munir Autos: 042-36310430 (located on Montgomery Road Lahore)
Madina Autos: 042-36361037 (located on Montgomery Road Lahore)
Kiani Autos Rawalpindi: 051-5530621
Btw, u dont need to worry regarding availability of spares. Just giving u example of my own experience.
Wind screen of my Nissan AD Van got a small crack (perhaps from some stone etc). I called Madina Autos regarding availability of wind screen. He told that it is available in Rs. 7000
In Rawalpindi, i checked it from Kiani Autos. He told 2 types of wind screens are available. One is of Rs. 7500 and other one in Rs. 6500.
So u can have mental peace of mind that even wind screen (which must be one of rare parts of these cars) of this car is available and that too in a quite reasonable price.
Just for comparison, wind screen of Hyundai Santro is costing Rs. 5500. I think Honda City etc would also be in this range.