Using my novel Centurion http://www.centurionnovel.com/, I made a test of FaceBook advertising and the Amazon associate program. I had a budget of $150 for the FaceBook ads. This meant I spent $5 per day for the ads on FaceBook. The way a FaceBook ad works is that you set a max per day expenditure and a max bid per click. Your ad appears on FaceBook pages at random based on your targeted audience and your bid. When someone clicks on your ad, you pay the bid amount. I let the system set the bid initially and adjusted it to $1 bid per click. During the month of August, I had 1,096,288 impressions (the ad showed on that many FaceBook pages) and 135 clicks (135 people clicked the ad and went to my webpage at http://www.centurionnovel.com/). The campaign cost me $107.75. I checked the visitors to my page at http://www.centurionnovel.com/ and the visits matched well with the clicks. The traffic on the site was up, but not that great. I had 4 sales through the Amazon associate program during that time and made $0.68. I did sell one book through the associate program, but not the targeted book. The targeted book was bought at least 5 times through Amazon (through observation of the author central pages). I have no measure of the number of books sold through other sellers. I won't know that until January when I get the royalty reports. There is no way to measure the effects of other marketing efforts. I turned back the amount per day to $2.00, the minimum, and will keep it there for a while. I'd like to keep the ad campaign going for at least 6 months. When my new book(s) come out, I will put one up as an ad campaign.
So, the conclusions. It hasn't hurt, but I'm not sure how much it helped. I'll keep it going at a low level, and I'll keep up with the Amazon associate program. The Amazon program doesn't cost anything and earned me almost 70 cents. If I were you, I'd try it too. Being an Amazon associate gives you some professional widgets on your site and can give you a measure of your traffic and sales. A FaceBook ad campaign will bring more traffic to your site.