I'm taking the CHES in October of this year. On the website for NCHEC, there is a http://www.nchec.org/exam/docs/nch-mr-tab4-155.htm
page which has a link where you can purchase study guides. The 2 guides cost $119 after shipping. The CHES exam cost $260. UGH. I better pass this thing!
I too am really concerned about this test. I wish there was a course I could take for the exam prep. I wish I could find people who have taken the test that would respond to inquiries like yours. In fact, I logged in here today specifically so that I could post a call for past CHES people to fill me in on how to study for the exam, and what to expect. I see that's a pointless endeavor, b/c no one is answering you.
Anyways, in my experience, getting this CHES cert is gonna be worth while. I already work in community health, and have my whole career, even before I was a nurse. Now I work in research in the chemical dependency field. Having certs like CHES are really useful, and look great on your resume and give you a leg up in hiring. An RN CHES is desirable when hiring a health educator. As such, you should definitely pursue this goal. I notice that Kaiser is often hiring RN Health Educators, so there's a well paying gig using all your specialties.
I wish I could tell you more, but that's all I've got. Good luck.