That would depend on:
1. Your computer specifications
2. Your budget
3. Your monitor resolution
4. Kind of games you like to play
There is a variety of graphic cards available today. It is not necessary that any 1GB card will run all games. For eg, you may get a 9400GT from nVidia for as low as 3,000 INR, but that's a crappy card and wouldn't really serve your purpose. A GTS250 from nVidia would run many games just fine, but will be more expensive.
Therefore, give us more details as stated above, depending on which we can provide some answers.