About 6.5-7k would be a quite FAIR amount, because a GTX260's worth these days is no more than 8k, while people are selling it for crazy 13k prices.
In your budget, there isn't anything good available in the market. However, if you have a relative living abroad, in USA etc ... you can get a brilliant deal for GTX560Ti's etc ... which sell around 14-15k there. If you really want to spend that much, then atleast aim for a 7950. Ofcourse you'll have to increase your budget for that, upto 35k, but its worth every penny. (Well, thats exactly what we mean when we say "Upgrade" 'eh?)
Other than that, in exactly 20-25k, there is NOTHING to spend on. Basically you'll be wasting your precious money on a 560Ti in pakistan, and frankly, its wroth is not more than 15k these days.