video proof ( ) the player oKyle scammed out of my item (the flash bio collection) i asked for 100 mil and got 10 mil then the player got offline with my item.
While I agree you were scammed , you have nobody else to blame but yourself for not being vigilant enough with your trade. Unfortunately, DBG/DCUO cannot do anything about it , submit a ticket and hope but you've just learned a very expensive and harsh lesson my friend.
On top of the previous posts answering you, you should know that any form of blacklisting players, no matter how scumbag they might be, is against the ToS. So you may get trouble on top for your OP. If someone is keeping a 0 short of the real price, give them max 45 seconds to correct, then press cancel, add them to ignore and leave, maybe report them for trying to scam (though that will be hard to prove). Losers like that thrive on the indulgence of society's understanding.