And today I saw this guy in kamadan selling 5000 stacks of war supplies:

I know that you can do a quest ( I forgot the quest name atm) over and over to get around 75 war supplies every hour. But I don't think this will explain the sudden price drop and people with 5000+ stacks.
I also thought about dupers, but since Anet claimed they already fixed the bug. And there a lot more other valuable candidates for dupers such as zkeys, armbraces , even lockpicks. So actually this reason doesn't stand.
The last reason I could think of for this is bot.
What do you think?