Prime Member can get 4 months Free
I have been the Amazon Prime member since 2012. I do enjoy the free 2-day shipping and Prime video. Then I realized as a prime member, you will get more benefits, like the co-brand credit card (5% cashback at amazon.com and wholefoods), and many extra promotions.
For example, as a regular member, recently amazon offers a free 3-month trials for Unlimited Music ($8.99 per month regularly) and Audible ($14.95 per month regularly). If you are a prime member and never subscribe these services before, you will get 4 months free. As always, I suggest you subscribe these free trials before you pay any real money. I believe 4 months are more than enough to experience and understand whether these services have some values to you.
Prime member link (Free trial for 30 days, then $139 per year or $14.99 per month). Apparently, you can subscribe the free trial first, then try unlimited music and Audible.