questions:
1. what brand of aftermarket brakes do you have, and specifically what? pads? drilled/slotted discs? or some sort of big brake upgrade?
2. are you singling out the front brakes for some reason? who did the work? if there is a specific reason for the front brakes to be bad i don't understand why the rears have to be done as well unless they are worn out.
a private mechanic quoted me $75 to machine four discs, including re/re, but my rears are almost at min. allowable thickness, and my rear pads are at below 50%, so there was no choice but to replace.
but as for the $1200 cost from the dealer... it sounds about right for 4 pads and discs, plus re/re labor, and it may also include having to bleed the brakes if necessary.