Website Teardown! (Yes I can do those)
The Motomaker site is wired with with an unused "extra cost" field so Moto can charge extra for certain colors. This is probably for the wood options.
The extra cost field is only on the back colors, not the front ones (and it's actually on the accent colors too, but that's probably just from a copy/paste.)
Anyway, WOOD! It's going to cost extra.