I like to get my hands on the cheapest edition I can in the best condition at that price. If the words in the book are the same as a more expensive one, I’m getting a better value, in my opinion. Then if it’s a story that becomes really important to me I might consider upgrading to a “nicer” or collectors version, and keep the old ones as lender books.
I just buy whatever is there at the bookstore… If we’re talking about how much I’m willing to spend max, I’ve spent >$200 for art books and I spent $150 on an art instruction book that used to be a reasonable price but since the artist/author died, the family is price gouging to get more money. I really loved the book (an instructor lent her copy to me) and so I just sighed and bought my own copy.