I know there are already hundreds of guides saying buy low and sell high, but one item in particular has been making thousands in so little time:
[Reins of the Crimson Deathcharger]
Thats right, our little duped friend can make you so much gold. Basically just spam trade every once in a while saying you are either buying it orr wait for that sketchy level 1 to advertise it in trade. They'll usually sell it for 15k and i throw it on the AH for 20-22k and it sells within the hour. I'm sure the price varies by server a little but you get the idea. I've made 50k ever since these things got flooded into my server. AND im on a medium population server, so theres your clue. Good luck