650 ti would be your best option and I am almost certain it costs less in india than 750. 750 and 7770 perform similarly with the exception of power consumption where the 750 wins.
Correct me if I am wrong , I checked many of the reviews about the gtx 750 , and almost all of them stated that the gtx 750 was on par with the hd 7790.
Also , surprisingly the 650 Ti is priced higher than the gtx 750.