If there's one major theme on these pages, it's that you can prepare for the social work licensing exam without spending an amount of money you're going to regret. It used to be exam prep could cost hundreds of dollars. That paid for audio CDs, for thick volumes of materials, and for practice exams. Now, with all the free resources on the web, that's just not the case. Audio comes free via a variety of amazing podcasts. Books full of info are made more-or-less obsolete by sites you know well, such as Wikipedia. There are lots of free practice exam questions scattered around the web, and if you want to take full-length real-time practice exams (recommended), it can cost as little as twenty-something dollars per complete exam (that's the case, at least, with SWTP's exams purchased with the bundle discount or with a coupon code).
Here are some of the sites mentioned above--and a couple of others for your clicking, studying, passing pleasure:
The Social Work Podcast
Social Work Test Prep
Portal:Psychology - Wikipedia
inSocialWork Podcast Series - UB Social Work
Psychology Basics 101
Social Work Today - Eye on Ethics:
Code of Ethics - National Association of Social Workers
Good luck with the exam!