I just had a quick look at the exam FAQ's for those that you mentioned and found here:
http://www.securitycertified.net/exam_faq.htm the following:
a. Since the exams test the implementation level skills of security professionals, it is strongly recommended that you prepare for the exams by taking the associated courses at an Authorized Training Partner (ATP). At the ATP, you will have the opportunity to work with the equipment and software that you will be tested on in the exams. After the class, and once you are comfortable with all the tasks in the courseware, you can prepare for the exam by taking a practice exam. The only authorized vendor of practice exam material is MeasureUp.
I would highly recommend that for any exam you don't rely solely on practice exams to give you the knowledge that you need to pass exams. if this was possible, the certification would be essentially worthless as people with no experience could easily pass the test just by memorising things. from the description above there will be quite a few practical examples that you will need to have more than just a learned-by-rote knowledge to complete.
in addition, you'll notice the section that I bolded in the above quote. if you're going to buy any practice exam, I'd recommend buying the one they authorise - there is a better chance that it will reflect the style of the actual one.
Network Pen Testing : Firecat 1.4
