Thanks for the post. A lot of useful info there.
I've been doing these ads for some time now, and to be honest, after the first month I slowed down on maintaining them by updating stuff and I've just let them run, because it was eating too much into writing time.
December was really fantastic for me with the ads, but I also interspered them with free ads on promo sites and paused them on the day of the promo, so it was difficult to get a handle on how it affected page reads.
Since December my average ACOS has risen from 11% to around 28% across the five books with a sale price of $2.99, in part due to increasing bids when everyone dived in and my ads ended up at the back of the pages. I've not run free promos on sites since to see how it made a change to results to try and discover what the ongoing organic page reads are from the ads. Bear in mind, before sponsored ads came along I was struggling to get any page reads at all and royalties were under $100 per month... way under.
It's looking as though I'll hit 30,000 page reads across the 5 books in February the same as January without any other type of promo. That's 50% down on December, but then you'd expect that because sales increase anyway in December and as I said, I ran free promos.
So basically I am earning $5 per day from page reads or around $150 per month using sponsored ads. I have to say though that this last week I've struggled to get more than 600 page reads per day and sales have noticably dropped off.
If I leave everything as is, then I'm making a profit, but it is small change, though not to be sniffed at.
I'm not sure what to do next with the ads as a strategy, other than in March, I think I'll try a series of free promos to see how that boosts things.
Basically, I doubt I'm ever going to be a mega seller of any of my books, but as it stands they will make around $250 in royalties after SA costs per month if I just let things ride with only sponsored ads for marketing.