I ran my Mirrors & Mist Amazon giveaway on June 3 and 4, 2016. In total, I gave away 320 books, which was about three times the amount during my last KDP event in April, 2016 (95 ebooks), where I only promoted my giveaway on free websites.
In addition to giving away 320 ebooks, I also sold 10 copies of my first book, Crimson & Cream, during the two-day promotional period (which is 10 ebooks more than I sold in the days before and after the promo). These indirect 'offshoot' sales covered the cost of the Bknights ad, and then some. I actually made about $10 profit on my $10 investment. My intent was to spend a little money to increase my giveaway volume, so experiencing a corresponding uptick in sales was an unexpected bonus.
Obviously, these are not staggering numbers, but my goal is to start small and work my way up to the more expensive promotions. I was very satisfied with my Bknights experience and ease of use in conducting the transaction through Fiverr. I'll definitely use Bknights again, along with experimenting with other promotional vendors.
Author Update: I'm currently editing the third draft of Warlock & Wyrm and am close to the halfway point (on chapter 15 of 34). My plan is to send the manuscript to my editor in mid-July.