Amazon prime includes access to tons of movies and tv shows as part of the membership. You also have access to all kinds of music. You just stream them through your Roku for the tv and movies. For the music I stream that through Alexa but I think you could stream the music through your computer or possibly your Roku as well. So far everything I've wanted to listen to has been available and it sure is cheaper than buying from iTunes. I've listened to tons of jazz, classical music, blues, 1950s, 60s and 70s rock n roll, world music, folk music, you name it, they've got it.
I love having Amazon prime. For a $99 per year you get all that and free 2 day shipping on anything you buy. For me it's well worth the yearly fee. But the thing that makes it worthwhile for me is that I watch the tv shows, movies, listen to music, and also buy things like art supplies and office supplies, and even some grocery items like tea, trash bags, etc. from them, so I definitely get my money's worth.
if you only order books from them and don't want access to their movies and music, you could always wait until you've got enough items to get their free shipping. That's what I used to do before they created prime.
Rob