A quick way to get some ideas is to go to your public library and look at trade published books. (selfpublishing.ca)
The average book published in the U.S. sells less than 2,000 copies in it's lifetime, and since bestsellers and heavily promoted trade published books pull up that average, you had better believe that the average self published book sells closer to 200 copies. (fonerbooks.com)
If it's that readers really are, for trade published books, favoring print, I'd like an idea why it's that way — is it because of their product placement in bookstores? (elizabethspanncraig.com)