This book is a must-buy for anyone studying for the LSAT--you really can't beat it. The math is really simple. Individually, these tests cost 8 dollars. There are ten of them in the book. So at this book's list price, you're getting more than half off for buying in bulk. On sale, it's about 75% off the individual price.
Buying jumbo size makes sense here, because the typical LSAT student needs to do many LSAT tests in order to fully prepare. I give each of my LSAT students in San Francisco (my company is called Fox Test Prep) between 7 and 21 real LSATs, and students frequently do more tests outside of class. The ten in this book are all very recent, real LSAT tests. There are no better questions to study than these, and ten tests worth is certainly not too many.
Even if you're just focused on one section of the test, this is still a great buy. For example, if you're strong in the verbal sections but are weak in games, you could buy this book and just do the games (there are 40 of them) and you're still getting a bargain.
If you're self-studying, you should consider buying TWO of these books--one for you, and one for your study partner. (If you're self-studying, you NEED a study partner.) You and your partner could each do one of these tests, timed, 35 minutes per section, and then you should meet to discuss your results. Work through the games together. Debate the Logical Reasoning questions. It doesn't matter if you're at the same level or not. If your partner is scoring significantly lower than you are, you'll still learn a lot--maybe more than he'll learn!--through teaching him.
You don't get many deals when you're on the LSAT/Law School path, but this is a really great one. Contact me if I can help!