where to find grammatix and rocket review books

<p>I've heard that these two books are the best for Critical Reading and Writing, which, in fact, happen to be my two worst sections. I was wondering where someone would find these for an affordable price.</p>

<p>If you guys also have suggestions for other SAT prep books in CR and W, that would be nice as well. What's your opinion on the book How to Improve your Essay in 3 minutes a day?</p>