>>8741831To add to what
>>8741923 said, there is an art to the casting process itself too. Japan is famed for its ultra-clear vinyl pulls, which have a crystalline, glasslike beauty that is unmatched by most standard mass-production facilities.
Basically it boils down to a lot of small operations and artists doing the work by hand, that's always going to cost more than some Kidrobot-style mass produced piece.