From the Super Mario Wiki
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Koopa's Shop is a shop located in the western part of Koopa Village in Paper Mario. It is run by a Koopa Troopa. Goombario's tattle on this Koopa Troopa states: "He's a Koopa Troopa merchant who sells goods. He also checks and buys stuff. You might want to buy some stuff from him if we're going somewhere dangerous."
Best selling prices
Names in other languages