I took TPR this past spring, and I thought the books they gave me were very helpful in my preparation. You get to keep all the workbooks and tests (6 total that they administer like the actual MCAT). After looking into it, I didn't take Kaplan for a few reasons: center was 45 min. away, wouldn't be allowed to keep the practice items, had to come in to the center everytime I wanted to practice with psgs, and class schedule was inconvenient for me at the time. Most of my friends had taken TPR and recommended it because they had really good teachers. If you are going to attend class, then a prep course may be worth it to you. But most of my class never came to any of the lectures and used the books at home (they said our teachers sucked, which I don't totally agree with). If that sounds like something you might do, then you may just want to buy the books from someone. As for Kaplan teachers vs. Princeton teachers, I've heard praises and complaints from both ends. I do know that at TPR the requirement to be a teacher is an 11 in each subset (one of my exam procters told me that).
As far as Berkeley Review is concerned, I bought all their home study books and I like the additional practice. They have ALOT of practice passages. I've seen alot of posts for ExamKrackers, you may want to invest in some of those for the extra practice. Good luck and PM me if you have any specific ques. about my TPR experience.