PM PrepCast and PM Exam Simulator were totally worth it. My only study materials were the PrepCast and PMBOK guide. I did take all 9 of the exams in the simulator. It helped me identify areas that I needed to focus on. Made notes based on PrepCast lessons and augmented them with PMBOK guide. Also read a couple of the standards (WBS, Scheduling). Made my own spreadsheet of ITTOs. Then sorted it by Inputs/Outputs. It was enlightening to see outputs from one process going into another process and so on. Best example is Work Performance Data/Work Performance Information and Work Performance reports. Draw it out, you will see what I am talking about.