nacholibre...Out of my personal experience,
PR is the easiest SAT reasoning prep book....KAPLAN's is the toughest one...if you score around 2100 in the practice tests of
PR, then u will probably score around 1900 in the tests of KAPLAN....
I have seen Official SAT Subject test Prep Books in few bookstores (one is opposite to ratnapark junction near Ghantaghar).