my budget is in indian rupee so it is as, 6000 indian rupee.please be sure that all price of product are more costlier than usa etc.(because of import charges)
radeon hd 7750 seems to be out of your price limit, msi radeon hd 7750 (dual fan) is around 8000 INR.
there is one 6770 for 6860 inr - msi 6770, currently out of stock.
sapphire 6750 1 gb gddr5 is around 6583 inr,
msi r6670 md1gd5 (radeon hd 6670) 1 gb gddr5 is around 5762 inr and is under your set price limit (but it's out of stock atm).
his radeon 6670 1 gb ddr3 is around 5208 inr.
check with your local suppliers for more/cheaper prices if you can. based on the price, msi 6670 fits your requirements.