Valve has revealed the final form of its Steam Controller and its price:
http://www.polygon.com/2015/3/4/8149643/hands-on-with-the-final-version-of-the-steam-controller
There are two touch pads, one on either side, that double as buttons. There are triggers, two bumpers, and two more buttons on the rear of the system on either side. That means that, ignoring the four face buttons, two touch pads and analog stick, there are six buttons on the rear of the controller.
The controller is coming this November, for $49.99
Here's another (and really big) picture of the controller, from Gamespot
Please excuse my bad English.
Currently gaming on a PC with an i5-4670k@stock (for now), 16Gb RAM 1600 MHz and a GTX 1070
Steam / Live / NNID : jonxiquet Add me if you want, but I'm a single player gamer.