Here are my results.
I started a Facebook ad campaign to get "Page Likes" for my author page. I planned to pay up to $2.50 per day for ads to bring people to my page and get a "Like". I ran the ad for four weeks, and this is what I got.
I muddied the purity of my study by a getting a 'wild hare' and boosted a post, right in the middle of this campaign and paid an additional $60.
I started the campaign with 22 page likes, which had remained unchanged since I first started my author page and sent out "like requests" to all my friends on my regular facebook page. I tried to add a comment to my author page everyday, but probably ended up posting once every two to three days.
After 28 days, here's what I got:
Paying up to $2.50 per day, I spent $68.27 on this specific campaign and they say I got 84 page likes from it, costing me $0.81 each.
From the 'wild hare page boost' I got 123 page likes for that specific page.
I now have 136 page likes for my author page.
During this time period I had 2 organic page likes from people I met on twitter, so there were 15 pages likes from other sources--possibly secondary to the 'wild hare boost' or from posts on twitter.
During this time period I had one (1) conversation with a person on Facebook from these new page likes. I cannot say that I have sold any more books as a result of either of the advertisements. I have had a hand full of Kindle Unlimited downloads and cash sales. If all of these were from the facebook ads, they would have a value of about $5.
So, I got one conversation and (maybe) $5 in sales from an investment of $128.27. Was that worth it? It depends on whether those page likes will read further posts, repost them, and/or buy my books.
Going forward. I will be interested to see if I continue to get any Author Page likes. My hope, all along was that this would build a momentum that would carry on a consistent page like increase. We'll see.