I didn't take econ in high school and I thought this course was really easy. Barely any hard math to do. (hardest would probably be gr 9 or 10 level in high school).
Easy concepts. Just keep up with the content each week and assignments and you can easily get a 90. The exam and midterms are harder than assignment questions, but if you can find some practice on older exams and midterms, you'll do just fine if not great
The prof (Holmes) is a relatively good and easy-going. She basically repeats what's on the powerpoints. So going to class isn't the highest priority as there are posted podcasts on elm. But if going to lectures works for you, go right ahead.
The textbook isn't really needed at all. The study guide is ok if you need extra practice with concepts. But don't get them if you want to save money.