Keep in mind not all “privacy coins” are private. Some claim to be private because they have a privacy mode or just simply use IP obfuscation.

All monero transactions are private. The sender, reciever and amount are hidden. This is a true privacy coin because of these three features.

ZCash privacy is opt in

Dash I do not consider to be a privacy coin but is called a privacy coin since it has a privacy send mode.

There is Firo which I have not used much but I believe its privacy is opt in

Zano is a privacy coin that looks promising.

For audiobooks I go to audiobookstore.com and buy gifts cards using a credit card and I buy the credit cards from Cakepay or Trocador.

https://audiobookstore.com/gift-certificates.aspx