I have bought a 32GB SanDisk Ultra MicroSDXC Memory Card 2 months ago for my Samsung mobile. Its a great value for money product. Its comes with various variants such as class 4, class 6, class 10, Ultra. Basically these are the performance measurement, it tells about how much maximum speed(in mega bytes) it can transfer per second. E.g if you bought a class 4 memory card than it can transfer maximum 4 mega bytes per second, similarly class 10 can offer you maximum 10 mega byte per second speed .
I am personally using SanDisk class 6 Memory Card. It offer 29.41GB usable space.It cost me 350 rps at that time. I am pretty satisfied with its performance and I have faced no issue regarding anything. I would greatly recommend this product.