Goto olx and Pakwheels used car section limit your search first on amount and model. And then make Hyundai or Suzuki.
Since you said you cannot spare time for repairs Santro is also a big no. I know many santro lovers would say a lot of things about my post but goto any Sunday add drive a santro sit in the back seat. Talk to the best mechanic you have and you'll know what I mean.
Finding a 04 Vitz in 7.50-7.75 is an option but khuda na khuasta the car is trouble some you'll get khuaar.
Consider the Suzuki used car scheme maybe you find a wonderful condition alto or a cultus.
With Alto and cultus you might have to let go luxuries but you'll be very happy
You can easily find an alto 2012 mid model for 7.50 so a 2010 should fit your budget.
Alto again looks good, the engine is rigid, Ac is very very good but is heavy on petrol good on CNG.
My suggestion would be a later alto or a year or 2 I.e 08 cultus stay away from 660cc specially if you have long journeys.
With Pakistan s security issues and every thing Alto seems to be a perfect upgrade after mehran rest is your choice