I stumbled across this controller after reading around on Reddit for recommended gaming controllers for mobile devices. Apparently it's a fight between Moga Rebel and the Mad Catz Ctrli for best controller.
I had decided that Amazon would be cheapest but then this MobileZap deal appeared out of nowhere from a Google search and it's at least $20 cheaper than anyone else.
I don't know an inordinate amount about the controller but improved control in Terraria is attractive to me plus I can apparently stream PC games through the KinoConsole app and the controller will make that a viable option.
Read more about the controller and supported games / apps at the Mad Catz site
P.S. I've just put my order through so I don't want to hear about any cheaper deals :-)