ETS writes the test, so you might assume their book on the test is the best resource for preparing for it. WRONG! It's just another way for them to rip money from poor teaching students. If you can, get a cheap used copy, try to find it in the library, or share one book among your classmates.
I just completed a master's program for a M.Ed. in secondary science education. While most of my graduate program was excellent, the course on teaching science was seriously lacking. I used this book to help me prepare for the Physical Science constructed response ("pedagogy") test. This book was far too general and too slim to be useful. It includes information on all the science pedagogy tests, and since each one is construced and scored different, any one reader will only find a few pages useful. There's only one practice test, which is insufficient for real preparation. Now I've completed my master's program with a 4.0, I've completed student teaching, and I've written a lot of good lesson plans, and yet somehow I've managed to fail the science pedagogy test TWICE after using this book as a guide.
I highly recommend instead of ETS' books, using the National Science Teacher's Association "NSTA Pathways to the Science Standards: Guidelines for Moving the Vision into Practice" and NSTA's "Tips for the Science Teacher: Research-Based Strategies to Help Students Learn." Using these as a guide an resource, you can determine how to construct goals, lessons, and assessments that will meet the standards of the test. I'm taking the test for the third time next week, and I'm much more confident now. The books I recommended are available from Amazon and the NSTA website.