The TOEFL materials from ETS are the BEST–they come with tapes, tapescripts, authentic scoring keys, and, best of all, REAL TOEFL QUESTIONS.
You cannot prepare for the test without REAL questions, and this book has lots of them –you will get a good idea of what will be on the TOEFL.
The problem with official TOEFL books, however, is that they do not give many explanations, they do not teach you grammar, and they do not give you any strategies to help you raise your score–they just give you the tests and you have to figure out what the test is like by yourself.
This kit has a lot of TOEFL stuff for you to get started. For people who already have a pretty good level of English, it is probably enough. For example, you should take a practice test, don’t cheat, follow the time limits closely, and find out your score.
Whatever score you get on that test is your real score. If you score over 520, your English is pretty good. If you score over 600, your English is great and you can probably learn enough about the TOEFL from this set to get the score you want
TOEFL Test Preparation Kit (CD+PDF)