So, full disclosure, I make shit. Between 1300 and 1700 a month, give or take, depending on commission. I sell phones currently. But, I only work basically part time (28-32 hours a week) and I sell phones out of a small Costco.
So far, combining my projected Kindle Unlimited page reads and my Kindle eBook and Paperback sales, I've pulled in about 550 in the first ten days, and sales have been steadily increasing.
Monthly, that's about 1650, give or take. Even if they decline a bit, I could still be seeing about 1300 a month, more if I market it harder, or release more books.
I am about 5K into the next novel in the series, and my first book was 110K words, so if I push hard, I could have another novel ready by this time next year.
I just use the platforms that are readily available to me, mostly Facebook and Amazon advertising. $20 got me about 8K reach on Facebook. I've got two versions of the book out, like I said, digital and Paperback, and both are performing okay, accounting for about 40-45% of the income. Kindle Unlimited is where I'm projecting most of my income. I've been steadily increasing page reads since I released on that platform. I peaked at about 11.5K page reads on the 11th, whereas my average is roughly 5500/day. KU pays by the page, and I'm looking at about $0.005 - ish per page, maybe a shade more or less. That's about $27/day there, with about another $22-$25 on actual book sales a day (some days sell WAY better). Put that together, low end, roughly $50/day since I started, based on my numbers, X30 days, roughly $1500. An average month where I work.