@mrkhan11 bhai,
Option 1
There is nothing wrong with Vitz. Just you have to be wary of the piece you are getting. That problem is easily solved due to the fact that we have the facility to consult with @Alta bhai (Altamash Murad) of Car Spot Karachi. Cell # 0333-2135567.
He can arrange a very fine Vitz 99 (around 430K) or Vitz 2000 (around 470K). All within your budget. No problem with parts. Atleast not in Karachi. Accomplished mechanics of Vitz, however, is an issue you may have to look into.
You can easily come down to Karachi, buy your Vitz from Alta have your car shipped and registered all at around 500K.
Down side of having Vitz is that the parts are expensive, with some of it's parts being quite expensive while others are slightly more expensive. Vitz repair turn-around time may be more than that of a locally assembled car.
Option 2
Otherwise Cuore is very good but has around 60K own on it. That will put it beyond your budget. Otherwise you would have to wait for 6 months on booking. Also post 2004 models are quality wise not as good as the previous models.
Option 3
Alto-VXR A/C CNG. Own is almost non-existent. Very good resale. More powerful than Cuore. Drive quality inferior to Cuore. Cheap parts and maintenance. Hampered with QA issues, like all PakSuzuki cars.
Conclusion
Make up your own mind.
Otherwise, my opinion is that if this not going to be your only car at home, buy Vitz. Else buy Cuore (if you can afford the own of 60K or wait for 6 months). If that too is not the case then buy Alto.