I did it starting ten years ago with printed books on Amazon Advantage, and put them on Kindle via KDP 3 years ago.
Here’s my Kindle page. Haven’t had any six-figure months, that’s for sure, but it provides a living.
http://www.amazon.com/s/ref=nb_sb_sabc?url=search-alias%3Ddigital-text&pageMinusResults=1&suo=1375792257070#/ref=nb_sb_ss_i_0_15?url=search-alias%3Ddigital-text&field-keywords=matthew%20bracken&sprefix=Matthew+Bracken%2Cdigital-text%2C289&rh=i%3Adigital-text%2Ck%3Amatthew%20bracken
