How to keep TTRPG source manuals in service

Short version- I want to fix TTRPG reference books myself with high quality repairs, keeping in mind the source books are currently only worth 30-60 USD each, but will soon be out of print and become increasingly hard to find (and likely priced accordingly).

I hear white glue is rather brittle and that doesn't sound like it will go very far with my usage patterns. I hear some folks say to go with PVA glue, which doesn't look prohibitively expensive, but wanted to get an idea if that will have enough elasticity for regular use (as my specific question).

I would also appreciate suggestions on how to keep my books going as long as possible. Thanks!