Lots of variables here, such as:
Number and type of parts needed -- is it just brake pads, or pads + rotors, or pads + rotors + calipers?
Quality of Parts -- not all brake pads are created equal, nor are rotors. There's bad, fair, good, better and best.
Type of Shop -- a dealer is going to have a higher labor rate than an independent shop, and a chain store probably cheaper than an indie shop (but by no means better).