Whoa whoa whoa wait a goddamn freaking second here mister weaboo
First of all the plate armor has extra plate on the bottom of the belly, thus, extra price.
Second the ''kingly'' is actually the cheapest? Why? There are only yellow/golden inlaids, no fancy coloroued gambeson over the mail, its directly plate on mail.
Third: Blue and Red dyes weren't that much of a pain to make either. And a gambeson is pretty darn cheap to have. So the 2 armors with gambeson shouldn't be that much more expensive than the mailed one, the blue one being cheaper than the red one due to the lack of golden decorations.
Now you could use that
http://en.wikipedia.org/wiki/Kermes_%28dye%29 as a source, but I doubt anyone would go around wearing something that pricey to go to war with.
So no, nothing to justify the better price, except perhaps higher quality textures.