A new book of 10 LSAT Prep Tests is available from the Law School Admissions Council (LSAC). Tests 52 - 61 are now available in one book!
This is great news because these tests include the new double passage that appears in the reading comprehension section. More recent tests may also be a bit more challenging than the older tests.
Visit http://www.lsac.org to shop for materials. Just click on "Services for Prospective JD Students" and then "Shop for Prep Materials"
And a word to the wise....never buy books from test prep companies! The best materials are available directly from the test makers themselves for very reasonable prices.