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 
