According to my knowledge, in Pakistani market there are 3 types of helmets. One is locally made with cheapest quality and ranging from 150-200.
Second one is China imported that start from 6-700 and goes up to 1500 to 1800
Third one is Indian imported that are highest in quality and recommended for heavy bikes. Indian ones starts from 2500 3000 and goes up to several thousands.
Major market in Lahore is Meclode road near Lahore hotel . Go to there and search for different shops.