I also enjoy buying used books where one can tell that the previous owner treasured the book over the years and made notes or highlights. However, the demise of the sewn binding – publishers have shifted to shoddy glued bindings even for prestige titles like the collected works of many poets – means that there will probably be less well-used and loved books around, since the binding is likely to give out already within the time that the first owner has the book.
Binding is something you can do at home with minimal equipment. I have a fair sized library with lots of old books; got into bookbinding as a side effect to keep everything ticking over.
Even acidic paper is something you can deal with, though it's more difficult than cutting off lousy glue bindings and replacing with something better.
