Its up for a short while, but the Bioshock Infinite pack is at 75% off all combined. Good deal. Also each individual DLC as well if you only needed to fill in some gaps.
All of them http://www.macgamest...e-Starter-Pack/
Clash in the Clouds http://www.macgamest...-in-the-Clouds/
Columbias Finest http://www.macgamest...lumbias-Finest/
Burial at Sea - Episode 1 http://www.macgamest...-Sea-Episode-1/
Burial at Sea - Episode 2 http://www.macgamest...-Sea-Episode-2/
And yes, these are all SteamPlay, so its redeemed on steam.