I would suggest the following three as the most important study tools. I scored a 522 and used these as the core of my studying:
(1) AAMC Practice Materials. $200 for their MCAT package. Practice questions produced by the same people who wrote the test!
(2) Khan Academy. Free and very useful for reviewing all the material very quickly. I watched every video at 2x the speed within a month of my exam.
(3) Kaplan 7-book series. Great for getting the overall content down.
Don't rely on just one method for your prep. It is important to use a variety of resources. If you need structure, then I would suggest hiring a private tutor rather than using a prep company. You can find freelance tutors for a quarter of what test prep companies charge for private tutoring. For instance, I tutor from
MCATSelfPrep.com. I am sure there are many other tutors out there as well! Best of luck!