The Lv. 50 PvP Gear on Dromund Kass (or Coruscant?) costs Warzone Commendations. The Champion Bags that cost 200 Warzone, and 200 Mercenary Commendations give a chance to get a random piece of Champion gear, or Centurion marks. Note: If you get Champ gear from the bag, it's gonna come with no stats, take these to your vendor and turn them in for the actual gear. (Ex. Unassembled Champion Legpiece can be traded in for the actual Champion legs of your choice.) You can also get Champion and/or Battlemaster bags from the Lv. 50 Daily/Weekly PvP quests.