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 you have a background in marketing and a passion for a particular niche, then organizing a virtual event may be just up your street. A virtual event could span across a day or longer. Individual live sessions would be run by experts in the field. And conference features would include live question and answer sessions, forums, and plenty of free giveaways. Visitors to the virtual event would pay to attend, so the more effective your promotion of the event the more money you would make.