I live in Pakistan and desperately want an Iphone 5S. I only have about $250?

I will buy from America and use it in Pakistan. But the unlocked version of Iphone 5S is $649 which is way out of my range.

Sadly, there's nothing you can do about that, as Apple isn't going to change the price. My advice is to buy one in a contract if you can, as most Americans do then you will get your new phone for free.

I would like to drive a Lamborghini but can't afford it. Let me share the solution to our problem. Be satisfied with a phone you can afford and I will keep driving a BMW.
Why wanting something you can't afford?

Your iphone will get stolen if you are using it in public esp in Pakistan.

It is only useful if you are traveling abroad and need to take photos, login on Skype and make videos.

Otherwise stick with your desktop PC or Laptop for general use.

For that amount you can only buy the old iPhone 3G, you can do 75% of the same things with it. Also why 5S. Even 4S can run exactly the same OS just the screen is a bit shorter & $300 cheaper also.
BTW it doesn't matter where you buy it whether US/UAE/ or Pakistan, all Apple prices are uniform except when you get it from a service provider with an expensive data plan (it will be locked in that case).