I'm going to start studying to take the psychology (and maybe either art history or macroeconomics as well) AP exam in May of 2012. I don't have a class so I have to prepare all on my own. But AP prep books are usually pretty expensive, unless you buy older editions. Is there that much of a difference besides slightly updated material in the newer editions? Could I get a good score by studying older editions?
Also, if you could give me some examples such as Barron's AP, Kaplan AP, 5 Steps to a 5, etc. for ones you have used and succeeded with, that'd be very helpful.
Thanks!