Premiere Pro CC 2020 Certification Practice/Study Material

Hello everyone, this is my first time posting and reading in these forums. In college they taught us Avid but I personally enjoy premiere better. I've been using it for a couple years now and I would say i'm at an intermediate level and would like to learn more and refine my skills. I recently decided that I want to study and practice so that I can prepare to get certified. However, lots of courses and reading materials have poor reviews indicating that they are a "Waste of money" and lack practice files to follow along. I was wondering if anyone could recommend a book or course? Preferably something cheap as I currently work part time.