Every Wednesday, Rocks in My Dryer hosts a carnival of things that make your life easier, appropriately titled, "Works for Me Wednesday."
I thought I'd throw my hat into the ring with a great way to supplement your library rather cheaply.
As an English teacher, I'm always on the lookout for adolescent literature with which I can stock my (future) clasroom. A few years ago, my parents discovered that there is a Scholastic warehouse in the city closest to our home that has semi-annual inventory sales. Since that discovery, every year around Christmas (and around one of their sales) we take a trip into the city to visit the store and I get to pick out books for my classroom. My parents are great to take along because their interests vary from mine and I end up with a wide variety of books, many that I never would have looked at on my own. As a perk, my parents often set a pre-established spending limit and we consider this one of my Christmas gifts!
So, to sum up, a cheap and wonderful way to supplement your library [or your child(ren)'s library], is to look into book warehouses near where you live and whether they ever have inventory sales that are open to the public.
Head on over to Rocks in My Dryer for more wonderful Works for Me Wednesday ideas!