You can sell your ebooks through Amazon's Kindle program or Apple's iTunes Connect, which gives you access to a large majority of the digital-book reading market and the barriers for entry are incredibly low. You don't need to invest lots of money to make this happen, but you do need to invest lots of time, not only in writing the ebooks, but in marketing them as well.
If it’s not clear yet, information and expertise are two of the most consistent and lucrative ways to make extra money online. If you don’t like talking on the phone, you can sign up to get paid to answer professional questions on JustAnswer. There are thousands of questions being asked every month from people looking for help from lawyers, doctors, mechanics, vets, and more. To apply, you’ll need to supply your professional verification, resume, and a form of identification.