But is it worth it if visits are not in millions?

There are some sites that generate decent Amazon Associates revenue without millions of visitors — it's a question of whether one of the main interactions users expect to make with your site is buying something from Amazon. Considering what you're building, it's worth at least experimenting with. Other booksellers (like Powells) have their own affiliate programs too.

thursdayb, you're shadowbanned (which is a shame, because that was a good comment). Might email pg and see what's up. Your comment history looks benign to me.

That was a good comment indeed! Thanks thursdayb, cheald!