Shadowsilk cost equation?

[Tarlek Flamehai]

So I would like to make Spidersilk (Und) armor or perhaps Twisted Silk (DM#348) armor from Shadowsilk (ToM), but I cannot figure out the cost equation for making armor from Shadowsilk. Can anyone help me?

Shadowsilk Masterwork Padded Armor 1500gp
Shadowsilk Masterwork Leather Armor 1750gp
Shadowsilk Masterwork Hide Armor 2000gp