Simple and Neat:
Bosses (between 3-5 Passcards when they drop)
Item Crates 2 and 3
Caergate mobs (drop pretty much any item in the game except mechs and Hypovials).
Mobs on Map (rare)
Daily Quests (Notice I say Daily, and not Repeat)
Janus and Turnpike Towers/Treasure Chests
Caergate Chests (1 per faction)
Purpose: To limit item supply, encourage teams, and to limit item supply (they do their job for the dungeons, but unfortunately alot of people think map drops are worth something).