RAM's bottleneck themselves to run on lower clock speed, if required. Get any cheap and decent DDR3 stick and you should be good.
However, amazon has a lot to offer.
Kingston 4GB DDR3 1333 Mhz: Amazon.in: Buy Kingston 4GB 1333MHz DDR3 SDRAM for Desktop Online at Low Prices in India | Kingston Reviews & Ratings
Corsair 4GB DDR3 1333 Mhz: Amazon.in: Buy Corsair CMSA4GX3M1A1333C9 4GB Memory Kit Online at Low Prices in India | Corsair Reviews & Ratings
Other: Amazon.in: ddr3 1333