Outercore and Core Performance Concepts are basically the same company. Outercore was disolved and CPC emerged. It's the same people running the company.
I have personally used their book & questions for my own PMP exam preparation and I can recommend it. (I used their 3rd Edition and I helped review their 4th edition as they were writing it.)
I've purchased the PrepCast and heard you give a recommendation to a company called OuterCore for study materials on the PMP Exam. This company is now owned by Core Performance Concepts, Inc. They have a PMP Exam study guide called "Achieve PMP® Exam Success, 4th Edition - A Concise Study Guide for the Busy Project Manager" published by J.Ross. It includes an Exam Simulator of 1200 questions as well.
Training for Project Management Professional (PMP)®, PMI Agile Certified Practitioner (PMI-ACP)®, and Certified Associate in Project Management (CAPM)®