Please define "brake job" Was it new pads? Was it new front rotors and pads?
Was it new calipers? Was there a brake fluid flush? What year/model 911? PCCBs?
Also consider that a dealer likely charges what, $100/hr?
If you have a few tools, and a desire to learn, you could do it yourself for a lot less.
Hangout here long enough and you will learn this