Amazon could be used as an addition Ad unit paying per impression
Except that would, in my case above, violate my first rule:
Do not annoy my visitors.
To explain for those who don't know me. My
educational sites existed long before the word monetising came into my vocabulary.
Because I was now retired, I couldn't afford the ever increasing bandwidth due to my site popularity and escalating traffic, I had to do something. Because I had recommended books to read, someone suggested I join the new Amazon programme. Jeff Bezos only sold books back then.
The commission on book sales covered all my outgoings with a bit left over for the occasional nice dinner.
There was no real advertising in the generally accepted sense, there still isn't. There never will be.
Five years later AdSense came along. I watched it for one week, and because of real time reporting I was induced to swap my Amazon book recommendations above the fold with AdSense. All done swiftly by changing one SSI file.
The rest is of course history. The next full day of AdSense equalled nearly one month of Amazon commissions.
In short? I still have one AdSense above the fold and little else. I still have Amazon links around my site where appropriate.
I'm in the education business, not the advertising business where I generate content like a newspaper to simply justify advertising.
In other words? I will not inflict more than one ad space on my visitors. My code of conduct, my choice.
If money was a dominant consideration to me, I'd go back to work as a consultant, across a number of disciplines, at some obscene daily rate. But then I'd likely have to cope with idiots, and this 72 year old is a real curmudgeon.
Sorry to be long winded.