THIS IS A REPOST, im sorry. Mabye this will help someone who has never seen it before. I DID write the whole thing myself and i thought i made it up.
Ok i searched for this and got nothing but if u find something please don't flame me, just trying to help.
1.) OK first off u need some money, any amount will do
2.) On your main character buy something from the AH that isn't posted more than once, for example a low level epic item or any blue.
2.) Buy it
3.) Repost it on the AH for more than you bought it for, for example if it cost 120g repost for 200g or less depending on your server's economy and what the item is.
4.) Now make an alt character and run it to the closest city
5.) Post in Trade chat: ( Example item: Twisted Chanter's staff, bought on main char for 100g reposted for 150g) WTB Twisted Chanter's Staff 200g PST
6.) Someone will see your offer and see the one posted on the AH for 150g
7.) One of these people is bound to see and opportunity to make money
8.) Once someone whispers you that they have one to sell you, quickly go and see if the AH still has the one your Main char is selling, if not ask them to meet somewhere
9.) When they come to you and open trade window say this "The money is on my main account, brb ill mail some to this char" (or something like that)
10.) Log onto your main account and see if the auction sold, if it did delete the alt char you used to post in trade with
11.) enjoy the 50g profit you made
(if it did not sell, make a new alt and try again)
I hope this helps you guys make some extra money, it takes a bit of work but its not against the TAC