if you take your car to a mechanic, for whatever reason, chances are you are getting ripped off. They all do it! All the time!
I don't know what car you're driving but front brake pads usually run for about $25-$45 for a set. Go to this website http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/home___ and search for brake pads for your car. Each front set covers both front wheels. Rotors go for about the same amount. It's takes about 10 min per tire to change pads and with any luck about 2 min longer to change rotors. You jack up the car, take off the tire and there are 2 bolts that hold on the calipers. Take off the calipers and compress them with a "c" clamp, reinstall the new pads and off you go. To replace rotors, there are 2 bolts that hold on the caliper bracket. Remove them and remove the two screws holding on the rotor. Replace the rotor, replace the caliper and pads and off you go.
Most shops charge about $80 / hr for labor so a legimate price for replacing your two front brake pads would be about $75 including tax and $150 if you do the rotors.
Most shops charge about $280 for the pads as you just found out because people walk in and say "how much do you want to charge to change pads".
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My advice? If you've never changed pads before, find a friend who has. Boyfriend, dad, husband, neighbor etc. Have them order pads and rotors from advanceauto. Buy them a 6 six pack of beer and some chips and given them an hour and your brakes will be fixed.
seriously.. I have a friend who took his car to one of those specialty brake shops. They quoted him a price of $1800 for brake pads + rotors on all 4 wheels. I had him buy the parts for $180 and I did the job in 1.5 hours. And you can bet the shop would have been faster. That means they were going to gouge him for labor at $1080 per hour.
that help?