How rare are golden Kanohi masks in BIONICLE?

Answer 1

Probably it's the Platinum Kanohi Avohkii. Also the Golden Kanohi Hau (14 karats) is very rare. Other rare masks are:

• Prototypes and rare Misprints (are very rare and only a few exists. Prizes are about $150 - $600)
• the Kanohi Rua (Chrome Kanohi Hau from the Power Pack)
• the Movie Edition Kanohi Kraahkan (Mask of Shadows) from the Takutanuva set
• the Misprints from 2001 (6 wrong colored Kanohi Ruru and Matau, and 2 wrong colored Kaukau)
• the original orange Kanohi Vahi (Mask of Time).
• the Kanohi Kraahkan Helmed from the Ultimate Dume set
• the Transparent Kanohi Avohkii (from the Takanuva set)
• the Grey Kanohi Hau (from the Takanuva set)
• the Transparent Green Miru
• the Coper Huna and Komau
• the Infected Kanohi Hau (from Muaka and Kane Ra set)
• the Poisoned Hau Nuva (in 4 differend designs)
• the Golden and Silver Kanohi (from 2002 mask packs)

Answer 2

They are pretty rare, because they are hard to find and were only avalible in the Mask Packs.