A KLONDIKE Bar
I know it sounds crazy but imagine a klondike vendor in wow.
Buy Price 50g
Sell Price 50g
you can add a bunch of them like a 20g one called mini klondike bar, and a 75g one Mega Klondike bar.
So you can buy it and give it to another player as a payment. So its like the famous phrase:
What would you do for a Klondike Bar?
Ill give you a perfect example.
Dps: Hey tank can you run me though a heroic please.
Dps: Would you do it for a Klondike Bar.
Tank: Yummm Lets go, invite.