There are fewer new readers of digital books, and they tend to consume physical books as well. (theguardian.com)
You can do these pretty cheap, and they're worth it to nab a few new readers. (draft2digital.com)
And, let's face it: you probably don't want to spend (or can't afford to spend) thousands of dollars on publicity and marketing which may be able to get you some coverage that might get you a few new readers. (mixtusmedia.com)