You can purchase here, from this site, or you can find Cloak of Protection at these stores:
AUCKLAND
Tiritiri Matangi Island
Waiheke Community Art Gallery, Oneroa
HAWKES BAY
Tauranga Art Gallery, Toi Tauranga
TAUPO
Taupo Museum
KAPITI COAST
Mahara Gallery, Waikanae (closed for a rebuild)
Nga Manu Nature Reserve, Waikanae
PORIRUA
Toi Store, Pataka Art + Museum
WELLINGTON
Expressions Arts & Entertainment Centre, Upper Hutt
Zealandia: The Karori Sanctuary Experience (also, Flight of Pollen)
Aratoi: Wairarapa Museum of Art and History
SOUTHLAND, FIORDLAND, STEWART ISLAND
Rakiura National Park Visitor Centre, Stewart Island
Fiordland National Park Visitor Centre, Te Anau