First things first, you must know how to use the Wrapping Paper dupe method.
You can find a guide on how to do that here:
http://www.mmowned.com/forums/emulat...ure-guide.html
Now, what you must do is, once you've unwrapped the stack of 240 duped items, put them somewhere in your bag, rather than sell it. Dupe another stack of 240 items, and put this new stack, on top of your first stack. Bringing your total to 480 items. Keep repeating this process, around 100 times. It's a very boring process, so I suggest making a macro to do it for you.
Now, once you've done that, you're going to have to do it again. So in the end, you'll have two SEPARATE stacks of around 240,000 items. For this next part you will need a friend.
Find a vendor, and have your friend close to you. Trade him all your gold, except for around 100 or so. (I think any amount will work, so long as it's at least 1 gold. Best to keep safe, though.) Now sell your huge stack of items. Once again, trade your friend all of the gold you just received from selling the items. Then, open the buyback menu, locate the item you just sold. It may LOOK like you need a LOT of money to buy it back, but it will be free.
Using this method, my friend and I were selling the stack for 370,000 gold, buying it back free, and repeating. We made around 30 million gold in a matter of minutes.
Note: If you have too much gold, you will buy the stack back for full price. Having under 1000 ensures you get it free.