It's collected in three omni's,
here's a trade list.
You can ignore the red lantern, glc, emerald knights & new guardians stuff for the story with Hal. Basically get the event books (Sinestro Corps War, Blackest Night, Blackest NIght GL, First Guardian, Third Army, First Lantern) except Brightest Day, and everything that's just Green Lantern (except when it cross into the event issues).
Wish they had a dc unlimited but they just announced that their trades are selling more than their floppies, so that's probably not happening. I'd say check the library or read Rebirth and see if you like it.