I've thought about this a lot.
You can buy the AAMC exams for about $200. If you need more online exams, you can buy TBR tests for $150. So for exams you're in for $350.
You can buy the best book for each subject (based on the many lists at SDN it would be EK verbal 101, EK Bio, EK Bio 1001 Q, BR physics, BR chem, and BR organic). That will run you about $300 new (can be found cheaper used, but not worth the hassle).
At this point you're into it for about $700. Courses in my area run from $1700 to $2100, so the question comes down to whether it's worth it to spend $1000 to $1400 for the classroom part of the course. I could hire a good tutor to go over questions with me for maybe $50/hour, so that would be 20 to 28 hours of private tutoring. I'm pretty good at biology, so I'd need maybe 3 to 5 hours to go over questions. I'm worried about physical sciences, so that will be about 20 hours. Organic isn't really tested that much, so I'm not too worried. Verbal reasoning is best learned through practice, so a tutor might not be much help. At this point, studying on my own versus buying the materials and exams and hiring a tutor as needed is about the same price.
For me it comes down to verbal reasoning, quality science teaching, and test strategies in the class. If the class has good verbal teaching and helpful tricks for the exam, then it's worth it to me. I'm not sure how I'm going to get $2K to shell out (actually $1700, because ironically enough the best course where I'm at is actually the chepaest too), but I'm going to find a way. I could study on my own and do fine, but if a course can help me get a couple more points (33 instead of 30), then it's worth the $1000 difference between studying on my own without any tutoring versus taking the class.