Barter's Swap Shop
From the Super Mario Wiki, the Mario encyclopedia
Barter's Swap Shop is a business operated by Barter of the Brothers Bear in Donkey Kong Country 3: Dixie Kong's Double Trouble! It is located in the northern part of the Northern Kremisphere, west of the base of K3.
Originally, Barter's Swap Shop is in a generic cabin with only a few tools mounted on the wall. In the Game Boy Advance port, it was changed into a storage facility featuring some boxes lying around, and shelves housing some items.
As Barter's Swap Shop is not a typical store, Dixie Kong and Kiddy Kong must exchange one of their items to receive one of Barter's. When the Kongs first arrive at Barter's Swap Shop, they discover that Barter has a No. 6 Wrench, which happens to belong to Björn. However, the only item Barter is willing to trade the No. 6 Wrench for is a Mirror. If the Kongs want their mirror back after trading it away, they must purchase it from Barter for ten Bear Coins.
In the Super Nintendo version, Barter's Swap Shop is mirrored while Barter has the Mirror. This gimmick was removed from the Game Boy Advance port.