I think the most rare Bionicle set is The Sand Tarakva. It's only a prototype, and there are only 5 of them.
Also the rare Kanohi (like the misrpints from 2001, and other special masks) and the old sets from 2001 are very rare.
There is not a rarest LEGO they are all the same amount in popularity. Trust me im a lego expert. Jk its the gold c3p0
The Platinum Avohkii is probably the most rare BIONICLE part (mask). It's about $ 7000.00
It should be the Platinum Kanohi Avohkii (about $ 7000.00)
Also the 14 karat Golden Kanohi Hau is very rare as well.
The most rare Kanohi mask is the Platinum Avohkii. The second most rare mask is the 14k Golden Hau. Also another rare mask is the Chrome Kanohi Hau (Kanohi Rua) that came in "Power Pack".
The Fisherman
The rarest lego minifigure for series 5 is the LUMBERJACK
The most rare minifigure in series 8 is the red cheerleader!
rarest minifigure is boat
Probaly the genie
Probably proffer quirell
To be honest, they are all pretty rare now as they aren't made any more. However, the Joker seems to be amongst the rarest! :)
The modern minifigure was introduced in 1978.
On ebay.com
buy
no
basiclly you cant only if that guy sells you his own. Jango is one of the rarest minifigure in the world. I have one and i spended more than 100 us to get it.