Is plum polymers more expensive than black poly?

Are plum polymer molecules mined from unobtanium?

Just wondering as I can find black poly AK pistol grips all over the net for under $10.00, but a plum poly pistol grip is never to be found for under $17.00.

personally, I think that plum is black dye that isn't mixed right or is depleted. Because I've dyed all kinds of polymers for the gun industry and depleted black turns out purple - or plum - for which I need to stoke it with yellow to counterbalance.

So plum may well have been an accident that turned out pretty cool. (Like my WorldWar II "classic Patina" color, that is now so popular, was an accident)