The listed material costs are unit costs. Head, hand and foot armor require 1 unit of materials. Leg armor requires 2 units of materials, and chest armor requires 3 units of materials. This makes a total of 8 units if you are getting a whole set. Gold costs are the same for each piece of armor. All Nightfall campaign body armor is basic armor with an empty Insignia slot. All Nightfall campaign head armor is +1 attribute headgear with an empty Insignia slot.