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.
Right now, maybe $50, but only because I’m renting a room in a house and don’t have space for a bookshelf. But if I had my own place and built an office with a bookshelf, I’d easily pay $200 for a hardcover version of my favorite books.