wow i have the same problem, i'm taking chem in november as well.
So i bought the barron's AND princeton review. Barron's is horrible. I mean, i know if i study it thoroughly, i could ace the exam. But frankly, there's no time...
If i were you, go through Princeton Review very thoroughly. Then do their exams, and do the barron's exams. Anything you didn't get, go back to Barron's and review it...
This is a really good thread for SAT prep books:
List of the best review books