Brake jobs are easy. I did my first brake job 4-5 years ago, and was nervous, but I've done 3-4 since (brother's vehicle, and I have been through a couple vehicles between my wife and I).
My thing with brake jobs is I simply buy new brake pads and rotors. In the midwest, it isn't terribly often that the rotor just slides off, so it usually takes a fair amount of force and a big hammer. I usually end up with one rotor that likely can't be salvaged, so I just order a bunch of good stuff online and go all new. And usually the part total is just a hair over $200.
Lately, I have been replacing brake fluid while doing the rest. It's generally a good idea and much easier to do while you're already down there.
That being said, if you still hire the job out, you ought to be able to find it cheaper somewhere. I'd figure a rough max of $200 for parts, and if you did it yourself I bet $200 would buy quality parts whereas $200 where you are looking is likely fairly generic.
I'd have to think you could find someone to do the work for $200 or so, so maybe a max of $400 all said and done, but that won't be a business. Business will have overhead of various sorts. I suspect in NJ the rates are much higher than here in the midwest.