Pontiac Repair: Pontiac Bonneville brake noise, pontiac bonneville, pontiac dealer

Question
I have a 2000 Pontiac Bonneville. I had new brakes and rotors installed in December.  In the last week it is making a very loud humming noise when the brakes are applied after the car has been driven for a while.  I had it at the Pontiac dealer and he claims that the brakes and rotors are fine and that it "might" be that the bearings are a little loose and they may be making the noise.  What is your opinion?  He is quoting me $400.00 per wheel to replace these. This is a lot of money for a maybe fix for the problem.  

Answer
Sounds more like a hard spot in the rotor or pad. Bearings will usually make noise when you take a turn. Take it to another shop for a second or even a third opinion because if the noise happens while braking, then it's doubtful that it's something other than the brakes.