I go crest as my school had a switch of eco teachers and my new teacher isn't too experienced. Although for eco I feel like tutoring isn't needed, crest helped in the sense that I was interacting with people that literally talk economics and that helped me get me to look at economics in a different perspective. If you do choose Crest your teachers should be all state rankers and it's a chill environment, I don't use Crest as my main source of eco study but as a supplement to help me understand whatever I don't get. But I would suggest asking your school to get Atomi, it is absolutely amazing and will teach you all you need to know without the extra sh*t teachers unnecessarily throw in while teaching. Plus all your subjects should be on it and you can learn whatever topic you want whenever. Not to mention it has revision quizzes that you can personalise and it uses questions from other states' senior exams that match NSW's syllabus as well has HSC questions for revision. For prelim I covered the entire course in two weeks because of Atomi