You need to check this with your local Sun education partner. There may be many in hyderabad. One I know is NIIT. The cost actually around Rs 8000/-. But NIIT was having some scheme recently and it was for Rs 4500/-. Others also have promotional schemes from time to time.Just check.
I am also planning to buy a voucher now. But then I heard the one-free-retake-if-you-fail scheme is taken off. I am too scared to give this exam, primarily because, for a financially poor developer like me 4500 Rupees is a little expensive. Any idea on when Sun might implement the free retake scheme?