Brakes can be trivial, or they can be a nightmare depending on how rusty and how seized the bolts and screws are. We spent $800 on brakes all around for my wife's Corolla (disks front, drums rear). It needed wheel cylinders in the rear, rotors, etc.
They put new rotors on it, but they warped within a week. Rather than taking it back and having to drop it off and pick it up and so forth, I changed them myself for about $35 and a couple of hours on a Saturday. They've been fine since then.
Oh, and on the serpentine belt. Around here there's an annual state auto inspection requirement. If the shop you happen to take it to says you need it, you have little choice even if its just surface cracking, etc. On my old Buick I changed it myself in such a situation and kept the old one as a spare in the trunk/boot.
Cheers,
Scott.