Listening audiobooks

I am not a tech person. I want to listen to 11/22/63 this summer. I am so confused about audible. So I have to pay $15/month plus but the audio book for $30? That's $45 to listen to one book. Am I understanding it correctly? Is there anywhere to get it cheaper? Remember, I am not a tech person so nothing too complicated to figure out and I would be using my phone to listen. I don't own a laptop. Thanks