They have this down to a science.
Good barrel, good chamber, good wood = service grade or better
Bad barrel and/or chamber, beat up wood = field grade or parts
Good barrel, good chamber, bad wood = special grade with their CMP wood
Once they categorize them, offices are pre-defined. Prices subject to change of course.
If they call them "special" or "unique" with some sort of new category, they'll create an equally new price.
My guess is that them go with the standard category and pricing.