Just in case you didn’t heed our advice and read the recommended thread (Guide to Sample GRE Subject Tests Published by ETS) above I will mention that many of the books with different ISBN numbers may be identical. Also, many of the different editions may contain the exact same exams. Also, some of these exams contained in the books above may be available for free as a download. This thread is designed to help us collectively uncover this mystery.
I'm not sure if there is anything new in the book links above. The Amazon reviews are informative but they don't say what sample tests the books include. Hopefully somebody with a copy of one of those books will find this forum and tell us. On one of the Amazon reviews someone mentioned that one of the books contained one and a half tests. I'm not sure what that means . . . maybe some practice questions in addition to a sample test.