It all really depends on what type of student you are: if you can self-motivate easily, and can relearn the stuff yourself, then borrow someone's books and do it yourself! I studied on my own, and picked up my score quite a bit. Since then, however, I have been teaching for the Princeton Review Course, as it's good money! I chose PR because I found their materials to be better when I was studying.
Honestly, what I find is that the students who are able to learn the material (or relearn) on their own get kinda fed up, feel as though they're wasting their time, and will oftentimes just argue answers with me for the sake of it. My feeling is that those people would be better served if they were able to study on their own for the same amt of time that they're sitting in class.
I however know some people who absolutely cannot budget their time wisely enough. For those people, they really should take a course, to ensure that they will keep up and learn it all before the test. Unfortunately, I think I'll have to do that with the boards!