You are asking about card prices in India, which is probably something it might be easier for you to do than me. I can point you in the right direction as to which cards might be within your price range but it is strictly a guess.
As you are running a Nvidia based board already that is a decent starting point. A recent chipset such as the one listed here:
tells me that you have a PCI-Express x16 slot onboard and can use just about any graphics card that your power supply will support. Good and gooder.
AS to which one I will suggest either a Nvidia card of the 9500 or 9600 series or the Radeon 4650 or 4670. These should all be in the ball park or cricket ground of what you are asking for in terms of performance and price. May well be a bit more or a bit less. They will all give you much better graphics performance than the current IGP on your board.
10 years building systems.