Don't have any Borderlands games in your Steam library yet? It might be a good time to head over and check out the latest Humble Bundle, which offers Borderlands, Borderlands 2, and a truckload of DLC on a pay-what-you-want plan.
Coughing up less than the average price (a little over $5, as of this writing) gets you the original Borderlands and three DLC packs: The Zombie Island of Dr. Ned, Mad Moxxi's Underdome Riot, and The Secret Armory of General Knoxx.
It'd almost be insane not to throw a little more into the pot, though, since paying more than the average gets you Borderlands 2, along with the Psycho Pack, Mechromancer Pack, and Creature Slaughterdome DLCs. Borderlands: The Pre-Sequel isn't part of this Humble Bundle, but above-average contributors also get a 75% off coupon for the third game, as well.
The rewards don't stop there: more content in the above-average tier will unlock with time, even for those who have already chipped in. Those feeling charitable enough to contribute $15 or more get access to even more DLC, along with a 25% off coupon for developer 2K Games' official store.