I used both Lambers and Becker for AUD. Garland with Lambers is one of my top four teachers. He lectures on the material and explains many multiple choice questions in a way that Becker never does. Garland also covers material that Becker does not cover. You can get the course for around $300. I would buy Lambers BEFORE you put out the big bucks for Becker.
Unlike the other exams, AUD is just memorization and a tricky word game. Only doing 3,000 multiple choice questions will put you into a position of passing. Be sure to do ALL of the AUD questions in "CPA Review For Free."
If you do not pass after doing those 3,000 multiple choice questions, then spend the big bucks for Becker. I rate AUD as Becker's best course and BEC as Becker's worst course.
Buy Yaeger for BEC. Cindy Simpson with Yaeger rocks! Cindy will prepare you for BEC better than Becker!