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.
Another good thing to look at is domain authority and core page authority. If your site has had a few redesigns, moved URLs, or anything like that, it’s important to make sure that the domain authority has carried over. It’s also important to look at the page authorities of your core pages. If these are much lower than when they were before the organic traffic slide, there’s a good chance your redirects weren’t done properly, and the page authority isn’t being carried over through those new domains.
Clearly, there's a lot of demand on Amazon, and if any product is going to sell, it's going to sell well on Amazon. But the goal here is to source the right products that will easily sell at the world's largest online retailer. Generally, products between $10 and $50 sell very well here. Just be sure to do the right market research before jumping on this bandwagon.
To get started with Amazon affiliate marketing you will need to sign up with Amazon Affiliates. Then subtly market products on your site that are relevant to your niche and will be of interest to your audience. Make sure you only endorse high-quality products. If your visitors make a purchase on your recommendation but are not impressed with the item, you could quickly lose followers.