Amazon’s advertising business is booming during the pandemic. It’s growing faster than its retail, cloud computing, and Prime subscription divisions—and chipping away at Google’s dominant position. – Financial Times

“Enormous power consolidated around a small number of major online platforms such as Facebook, Amazon, and Google will jeopardize future independence for authors. These dominant platforms wield their supreme power to stand between you and your audience. We’ve traded one group of authoritarian overlords for another. These platforms are the new gatekeepers for indie authors. And access comes at a cost: advertising. – Mark Coker, CEO and founder at Smashwords

I was an early advocate of advertising books with Amazon ads. In my experience, the most effective and economical marketing solution for making a book known is with Amazon ads. When I ran LPC, Amazon ads served as our core marketing strategy. Our goal was to receive $1 in revenue for every 30 cents invested. Many times we could invest as little as fifteen cents to earn $1. Those days are gone. Now many Amazon ads only break even (invest $1, receive back $1). Still, if your goal is to make your book known and you do not mind losing some money in the process, Amazon ads remain a good option.

Based on my experience Google, Facebook, Twitter, and Instagram are poor ad dollar investments. This makes sense when you think about. These platforms appeal to a large audience. With Amazon ads you target readers of print and Kindle ebooks and from within that market, you aim for niche category readers.

Bookbub is another advertising option, though again I have found Bookbub ads to be less effective than Amazon. Bookbub also lacks the granular diversity necessary to tailor your book’s add to a specific set of readers. For example, YA and middle grade are two segments, but there is no genre distinctions beyond age. An ad for a YA coming-of-age novel will appear along side YA mystery and romance novels.