I agree with Sam, I used ARCH last sitting and was very pleased. It covers the whole syllabus, so I thought it was good value. They have their first chapter available for free at their website, as well as a studynote summary that is new to the CAS version of Exam 3.
For a more "high level" guide, I would recommend Actex, as this has perhaps more indepth mathematical treatment of the material, and really good exam like questions, but if you've been away from the exam process for a while, or haven't seen this stuff before, may not be ideal.
Just for completeness, I am using BPP for Course 4 (it's excellent), and have heard their material for Course 3 is similarly quite good. They have their first part of their manual for free download at their website as well. They claim their materials are a substitute for the texts, and a stand-alone manual, but it's very expensive as well.
If money is an issue, use Arch. If it's not, decide between Arch or BPP based on their free samples. Hope this helps, and good luck studying!