You see that section on the page that says "Buy" ? Those are your options, and they're all reccommended because those are the official stores the makers of the gamepad are promoting.
And if you're not using it for a tablet, but instead a phone, then I recommend a gamepad, generic or commercial, that will hold your phone in place, especially if you're willing to spend excess of $40 for the FC30.
A simple clip that holds your phone on your gamepad makes a world of difference in comfort. Right now the Moga Pocket is cheaper than the generic off-brand gamepads, and is sold on Amazon, which is very trusted, and fast ship times if you're near a warehouse. Orders of $35 get free shipping, so you can literally get two moga pockets for a couple dollars less than one FC30, or buy a Moga plus a Sanyo Eneloop base with AAA.