Pay-per-click advertising has revolutionized online promotion, and has been wonderfully effective for many Internet businesses. The prime advantage of pay-per-click is its ability to deliver your ad to targeted audiences. Unfortunately, like other forms of advertising, pay-per-click is seldom a cost-effective technique for marketing books.
Although pay-per-click can bring targeted traffic to your site, it's unlikely you'll convert enough of those visitors into buyers to make your ad campaign worthwhile. Google, for example, will charge you 75 cents or more per click for competitive keywords, and only a small fraction of those clicks will result in sales. Even if you're paying as little as 10 cents per click, your advertising bill will likely exceed the revenue from sales, in the experience of many publishers. With typical consumer books, there's just not enough profit margin to pay for the ads.