It is definitely
not necessary to purchase mock exams in order to score well on the exam. But some people find the additional practice helpful, so whether this might benefit you depends on how you feel you are doing with the resources you have now.
I think the most important factors are to have a introductory foundation in
Java before you start preparing for the exam, then use a good book focused on the exam, write lots of
test code, and use mock exams to help determine how prepared you are and where you need more practice.
[ November 23, 2007: Message edited by: marc weber ]