Amazon is doing a sale where if you buy 3 books that qualify, the lowest price is free.
Here is my referral link: https://amzn.to/3lHpW1O
Because I am building a physical book collection of hardcovers, and because my ex took most of the hardcovers with her, I have to essentially build my library from scratch. Because of the way it was structured, I had be careful about grouping my purchases into groups of 3, so that the lowest wasn't too divergent from the other groups of two.
The section I found of particular interest was under Books --> Literature & Fiction --> Classics
I then selected only Hardcovers, except in Children's books.
Here's the list of books I purchased from cheapest to most expensive. Happy hunting!
They added more, so I purchased about 30 more books. Here's the updated list.