Since we have a trading system there could be some achievement for it.
As example:
Using trading system for the first time
Complete a number of trades
And as reward there could be titles like:
Trader
Tradesman
Wholesaler
I suggest a new achievement in general and especially as seeming perfect for all teamkillers:
C*nt: Earned by killing a team member on purpose
I guess i dont need to say more bout.