I'm sorry, but the books--though they do contain their course strategies and real LSAT questions--are NOT worth $600. I know the feeling of not being able to really afford some of these pre-law expenses (unlike many people who are STILL going to insist you should take the course) and also the feeling of not really having prep courses in your area.
So I'd say that, instead of paying $600 you don't really have and/or can't really afford to dish out on some books, you need to go to ebay or post around different message boards and see if anyone has Powerscore course books they will sell you. I think the highest I've ever seen someone want to sell their books is $250...still expensive, but still cheaper than $600.
OR get the Weekend Course book. Someone sold theirs to me ($45) not long before I took the LSAT, and it is a pretty good book with many strategies in it. By the time I got the book, though, it didn't have anything in it I didn't already know as far as LR, which was my biggest problem section, and LG because I studied the Logic Games Bible (and if you study the Logic Games Bible, you don't need ANYTHING from Testmasters or Powerscore or anywhere else as far as the Games section goes). And nothing helps with RC--I mean, the book had some helpful underlining and circling strategies, which I employed and gained another 2 points RC practice (bringing my total missed to 2 in RC). I can't see the full-length books saying anything that much more than the Weekend Course book, only maybe a little more in depth, but it probably has more real LSAT questions in them...which you could get for less than $600.
I advise that if you pretty much suck at LR and don't really know the strategies/categories of fallacies and questions, learning what the Weekend Course book has to say will be helpful to you...then it's just practicing on real tests (which was the point I was at when I got the book--I was beyond strategies because I pretty much knew them all and honestly didn't need to spend money duplicating with the real questions in the Weekend Course book since I had all the real tests anyway).
If it's LG that's your problem, get the Logic Games Bible from Powerscore--again, a duplication if you get anything else from Powerscore because the Powerscore Weekend Course book, as well as their full-length books, will have the same Games strategies and the same LSAC questions.
RC--good luck there. All I could think to do was underline whatever I could predict a question being related to and make sure I acted interested and paid attention to the passage and just keep practicing that on subsequent passages. Not one book or course helped me there (I took Kaplan but had books from all of the four major courses).
If it were me--and, at one point, it was and this is what I did--I would take $600 (or less) and spend it on getting real tests from LSAC, going to ebay and getting the CD of explanations for all the tests, trying to find the prep books from Powerscore for cheap on ebay or anywhere I could get it (including the LG Bible) and maybe buy some other really good commercial books. If you look on ebay and don't see them, keep looking because someone will eventually put up an auction. I don't know what you're practicing at now, but I raised my score over 20 pts on practice tests without spending thousands of dollars (because I didn't have to pay for Kaplan, and if I had to, I wouldn't have taken it). I considered spending $600 on the Powerscore or Testmasters books, too, but ended up not doing it and I am expecting a good score on the June test. Nothing's really going to help you "master" the LSAT, but as long as you do a lot of practice tests and scrutinize what you get wrong (and some people also suggest you go over what you got right, too, but I hardly did that), you can do well on the LSAT.