People just don't know how to play the market. The only tactic they know is "undercutting". Like in this example:
http://i.imgur.com/mAM1Ldl.png
For some odd reason, the guy indicated by the orange arrow undercut the other guy below him. I guess he was in a hurry to sell, what doesn't make sense is that he then proceeds to undercut himself, and then more people follow and keep undercutting the undercutter (red box).
So what I did was simple, buy everything in the Green box and flip it for 380, making profit from other people's darksteel ore.