You did not say which city you are from. Usually most cities have a market selling scrap car parts (Bilal Gunge - Lahore, Cha Sultan - Pindi, Shersha - Karachi) Your car repair shop will know where they may be. You need not worry yourself with going about getting the doors. Ask the repair shop to do that for you. Only thing to guard against is being ripped off by your repair shop with regards to the price of the doors.
Having said that sometimes the used car market prices almost rival the brand new part prices.
