Were the all four replaced at the same time, the last time you did it? It is odd that your fronts did not wear and rears did. I fell in dealer trap once before and had them do it, but the 2nd time around I just paid $500 or so for all four, new pads, new rotors and labor. Remember dealer will not replace the rotors, they will just resurface them, basically grind them thin.
Do it yourself? I wouldn't recommend it no matter how much you save. This is brakes, line between life and death when that truck stops short in front of you. Get it done properly with warranty.
Where did you go to get your pads and rotors changed?
I'm thinking I should now head back to the garage where I used to get my previous car maintained. The place is called "Prince Auto & Truck Svc"