All you need for this scam is one friend to assist you, a decent item that is BoE, and you're all set.
How the scam works:
Get your friend to go to a certain victim who looks rich enough, and make him whisper "I'm buying (the BoE you are selling) for 500g, do you know where I can get one?" Make sure your friends buying price is more then your selling price to make it seem like a good deal.
After your friend says that, go to the same person and mention your item you are selling for less then his wanting price. The person may or may not buy the item, but if they do your scam worked. Now when the person goes to your friend and says "Here, I got it, gimme that 500g for it", make your friend say "Sorry, just bought!" and then you're done. Now you walk away with an extra 50-100g+ depending on how overpriced your item was.
To sum this up in case you don't understand: You take an item such as a BoE shield and say selling for 50g. It is really worth 25g though. Ask you friend to pick a victim and tell them they are buying the BoE shield you are selling for 100g, and then say "you know where I can get it?" after that the person will probably say "sorry, I don't know where" and then you leave. (BUT make your friend stay sort of close to the person.) Then you go over with the BoE shield and tell them you are selling for 50g. If the person remembers, he/she will buy it to sell to the other person for 100g,thinking they make a free 50g. After you sell it to the person, leave. When the person goes to sell it to your friend, make your friend pretend they already got the item they needed. And then you're done.
Hope you guys understand, I don't think this could get you banned.