Money Money is a badge that increases the number of coins that Mario receives after battle. It uses 5 BP.
In Paper Mario, this badge can be purchased for 20 Star Pieces from Merlow.
In Paper Mario: The Thousand-Year Door, this badge can be traded at the Pianta Parlor for 234 Piantas after getting the Platinum Card. It can also be dropped from Dark Boos in the Poshley Sanctum.