I spent about $45 on Facebook Ads targeting clicks to my book on Amazon. I paid around $0.30 CPC, and 155 clicks in total, but I couldn’t track how many sales were from Facebook, and I didn’t see ROI because I estimated 3–5 ad-driven book sales, which is at best $9 per additional sale. The other issue is that Amazon doesn’t tell you anything about who’s viewing your page or referral sources, so it’s hard to close the loop.
Also, I know from my personal experience that when you only do something because you think it’s a money-spinner you end up nearly killing yourself to get the idea over the line. I remember creating a careers advice site that bored me to tears. Every word I wrote, hurt a little. All 200,000+ words! Do not put yourself through this pain. I know I won’t ever again.