I would recommend a slightly different approach.
Making flash cards is one way to get to the underlying knowledge, say the different formulas in math, although I would prefer to learn these formulas "on the job" meaning look up the formula - or better yet prove it to yourself - while you are doing problems.
The GMAT is really not a "memorize-able" test. Once you have the formulas down you will have the tools but not the process and not the reasoning.
I would recommend that you get some good materials that will help you to develop an approach to each type of question. You cannot afford to have all of the formulas and grammar rules memorized and yet have an approach that allows for mistakes.
To me the proper approach is the most important thing. How do you begin each and every sentence correction? What are the first several things you do on every data sufficiency? How will you avoid the most common errors in general and the errors that you most often make in particular?
For that matter, what are the avoidable errors that you most commonly make? Assumptions? Calculation errors? Answering for the wrong variable? Forgetting to consider things like non-integers?
You see it is not enough to be able to get problems right. You need to have a strategy that allows you to answer correctly every problem that is within your ability to answer. If you miss some exotic and difficult problem this will barely impact your score. But if you make careless errors and miss several problems that you should get right it will be devastating.
At $200 you can get a range of written materials. You should certainly have the Official Guide 12th edition and the Verbal and Quantitative Reviews, 2nd edition if you do not have those already. You will also want to get additional materials that help you to develop the methodology that I mentioned above.
Your first steps might be to review anything that you have already done to see what types of errors you consistently make and to see where the holes are in your knowledge base. It might even be appropriate to make a few of those flash cards!
What is a general study format you suggest if I'm giving myself 3 months and a $200 limit for materials. What are the best test books? I think the best course of action may be to just do a lot of questions and create flash cards? Would appreciate any advice from people who have scored high marks.
