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.
5. Fiverr – Fiverr is a great place to make a few bucks or spend a few bucks if you need some of the services people offer. Basically, everything is $5. You either pay $5 or charge $5. They call them “gigs.” You can offer your services however you choose. If you sell art and you’re fine selling pieces for $5 each, that’s a gig. If you’re a graphic designer and you want to offer your services for $10/hour, simply offer a 30 minute gig. If they need two hours of graphic design, they pay you $20, or $10/hour by buying four gigs.