Using a memory card is the most affordable and easiest way of expanding your phone's memory instantly. All these SD cards are meticulously designed to withstand adverse conditions. They are shock proof, x-ray proof, temperature proof and waterproof. A 4GB SD card can be procured from online shopping sites like Amazon, Flipkart, and Infibeam. You can also use our price comparison tool to do a discount shopping. If you are lucky enough, you may even find cashback offers and exchange deals that further facilitates you to buy the product at the lowest price.