This requires two people. First go to the bar in BRD and buy however many Sulfuron slammers that you want in marks Sulfuron Slammer - Item - World of Warcraft Second go to halaa and take it over if you dont already own it. Next find a friend that wants marks as well. Go stand at the GY in halaa and duel your friend. Once your friend has beaten you to within an inch of your life and will kill you in one or two hits then drink a Sulfuron Slammer right before they win in the duel. The drink will tick and kill you while you have 1hp left. I farmed hundreds of marks within a couple hours this way.
EDIT
I forgot to mention that you should strip and then just spirit rez at the gy so you dont have to wait for the timer from dieing so much.