when brake pads get low they squeak, some have squealer bars , some have metal flake in the pads themselves to squeal when low. a rock caught between the sheild and pad can also cause squealing.pads can cost anywhere from 25.00 a set to 100.00 a set so no1 can tell you if thats a good price not knowing what they are installing.goto more than 1 shop or use a shop that you or a family member trust. it is common for the shop to charge 1 hr labour and the rest is parts. i can change both front pads in my driveway in 30 mins or less.