Aqua mask and Backbrace/Backpack
Pyro Jo – Level 80 Engineer – Darkhaven
You get a level 80 Masterwork back item (you choose from 3 different types) from one of the last story quests. Other than the starting backpack, lvl30 (or was it 40?) story quest, and guild back items, I’m not sure where else to get them.
As for breathers, I’ve never seen them outside of Karma vendors (I could be wrong), nor have I ever felt greatly compelled to hunt down anything beyond those. (Sorry, don’t remember which Karma vendor I got mine from.)