As in many other aspects of life, when it comes test prep, what you see is not always what you get. When a sales person tries to sell you test prep packages, be perspicacious. Before you write the check for thousands of dollars, ask about pedagogy. Ask to see the degrees your instructor is claiming to have. Ask to see written records of student averages under the tutelage of the instructor whose services you are buying. Test prep is an unregulated industry; some of the most successful and expensive businesses are the most fraudulent.