I’d stick with Amazon if I were you. All of my Amazon sites only have Amazon affiliate links. If you use Google Adsense display ads on your site, you’re literally taking people away from your site for the sake of just a few cents with these type of ads. If you direct them just to Amazon, then you have a greater chance of earning more money from that click.
If you are struggling to find exactly the material you are looking for, try Open Culture’s listing of free online education courses. The page highlights 1000 lectures, videos and podcasts from universities around the world. The site features a lot of material found only on universities private sites, all in easy to browse categories. This means you can find hundreds of university courses, without having to visit and search each university’s own site.
Before I talk about some of the methods for making money online, I wanted to address the role of pain versus pleasure. Every decision that we make in life is weighed on a pain-versus-pleasure scale. We will always do more to avoid pain than we will to gain pleasure, plain and simple. However, this is also what holds us back from succeeding in any endeavor.