Nearby used bookstore for most purchases or browsing. It sounds geeky, but I like how weathered books smell. It also gives me an excuse to wander the aisles checking if there are any cute, petite, indie literate redheads with glasses. I have refined taste.
For anything more than 50 years old I use the UC intercollege library network. Most books are only RFID coded in the bookjacket, which means you can carve out the tag with a pocketknife in the bathroom without damaging the cover and just stroll through the scanners on your way out. Granted it's something of an asshat thing to do, but my leanings are antique enough that no book so liberated is checked out more than once every five years. I'm a bad person.