Sapphire HD 4890 costs about 12K.
Sapphire HD 5770 for 11K.
GTX 260 costs around 10.5K.
4890 is the best among all of those and probably the best card for 12000Rs.
So get that.
But you'll need to check your SMPS.
It should be compatible.
And what resolution you'll be playing at?