SF_IS350

Hi, Any suggestions on how much brake & rotor replacements should cost? Lexus of Marin wants $1,400 which seems totally insane. I only have 20k miles on it, and they already replaced the front pads for free after 10k. I live in the hills of SF so I burn through brakes. I'm thinking of replacing them myself...never done it, but looks simple & I'm mechanically inclined. Am I missing anything? Thanks!