Titles worth reading that are not available on DCU:
-the Before Watchmen trades
-Green Lantern: Earth One Volume One
-The Sheriff of Babylon
-Shazam!: The Monster Society of Evil
-JLA: Earth 2
-Dark Night: A True Batman Story
There’s alot more books (a ton of Vertigo in particular) but the above are the tip of the iceberg. Most titles are $5.99.