Well, if you are in karachi, you can go to cooperative market and find shops dealing in this... I found one great supplier, his website is:
The cost, if somebody is selling you Arduino on higher price, then he might be selling it rgiht... If you go downt he road of buying yourself will cost you similar like that... I calculated, if you buy from anywhere in the world, and wanted the electronics items in Pakistan it will cost you Shipping + GST + Customs Duty... so if you buy $250 worth items, it will probably cost them around $50 to ship you, and when it has arrived in Pakistan, the courieer will ask you to pay another 25% of the total amount, so the total amount that you will be paying will be around $375. My numbers might not be correct but still you will be paying a lot more than what you see on online stores.
Anyways, a goodnews is that, we can buy Arduino Clones, you can go to the website, call the guy and you will see he has some good rates.. I he sells UNO under 1400 which is almost half of the original.
I hope I have answered you...