I am tutoring someone in it and can’t find full tests except two in a book the student bought. There are short quizes online. I would prefer something that could be printed out in full, so that we could go over it.
The REA book is excellent. Also, some materials for the AP Calc AB exam may prove useful, but I can’t think of their names of the top of my head.
There are also Peterson practice exams for almost all of the CLEP subject tests. Some public libraries have a subscription to a database (Testing & Education Reference Center) which would allow you to have access to these practice tests for free (if you are a library card holder).
Just a caution that these exam questions are written/designed by Peterson and not CLEP, so you can’t assume the CLEP real exam will be a perfect match. Good for additional content and questions.