@ Op : - AMD has reduced the price of HD7850 2GB to $200 but as price is here always on higher side you may have to pay a little over that and this may take at-least two months.
HD 7850 is the best option to look for.
If you are looking for something cheaper then go with GTX-560. Costs around 10.5k and performance is similar to that of HD 6870.
Don't buy from XFX as there are warranty problems. And don't buy the 6870, save some and get a better card from Sapphire or MSI (solid warranty service in Kolkata).