I agree with manchester; if you are not going for performance oriented parts, the local supplier is the place to go.
Example;
GM Parts Direct lists a front rotor at $38.42 and rear rotor at $36.16.
Autozone lists both at very little more money, and you don't have to pay shipping.
Another way of looking at this would be if you took the vehicle to a local, trusted garage for the brake job they would be using parts from Autozone, Advance Auto, NAPA or a similar supplier.