Force Unleashed Sith Robe
The story and action of Star Wars®: The Force Unleashed™ expands with the release of Star Wars The Force Unleashed: Ultimate Sith Edition, a special new version of the game that will show gamers the deepest, darkest side of the Force in a story that puts them on a collision course with Luke Skywalker himself.
Okay, so while the title says 'Costumes Guide' there aren't that many that require actively hunting down. Never the less, here is a complete list of each costume and how to unlock it:
Training Gear - Start the game.
Heavy Training Gear - Unlocked after beating level 1.
Light Training Gear - Unlocked after beating level 2.
Medical Robe - Unlocked after beating level 3.
Bounty Hunter Disguise - Unlocked after beating level 4.
Corellian Flight Suit - Unlocked after beating level 5.
Jungle Combat Gear - Unlocked after beating level 6.
Industrial Explorer Outfit - Unlocked after beating level 7.
Jedi Adventure Robe - Unlocked after beating level 8.
Kento's Robe - Unlocked via Holocron on Kasyyyk. As soon as the cutscene in the hut is over turn around and the Holocron to unlock Kento's Robes is in the tree stump behind you.
Sith Robe - Unlocked via Holocron on Raxus Prime. Near the end of the level,fter you defeat the first giant robot and use the jet engine to weaken the scrap to pull into the chasm, cross until you reach the end (just after you bend the metal sticking out of the walls) and forcepush the girders directly infront of you. Jump out onto the metal plate and bend another chunk of metal sticking out of the wall so that you can cross over to the Holocron.
Sith Stalker Armor - Unlocked by beating the game as Dark Side (Kill Vader).
Ceremonial Jedi Robes - Unlocked by beating the game as Light Side (Save Rahm Kota).