All excellent ideas. Little Free Libraries are fun! Also, when you go camping, bring books along for all ages and leave them out for others to enjoy.

I donate my used books to the library sale of used books.

I buy from my local thrift store then return the books when I'm finished. The owner gives me credit towards more books

I buy used books at yard sales and at thrift stores. I swap with friends and use the e-reader app on my laptop. I read a lot of free books from Amazon with it.

I purchase very few new books, cannot remember the last time, I buy used from my church fair, my library book sales 2x a year and borrow from family and friends, then my books are given to them or the two book fairs to be purchased by others, constant recycling is the best way...