"Certain kinds of armor are made according to arcane and esoteric methods that involve weaving magic into the substance of the armor. These masterwork armors never appear except as magic armor (see page 227), and even then only at the highest levels (16th and above). The various kinds of masterwork armor fall into the same categories as mundane armor and have similar statistics, but they have a higher armor bonus than their mundane counterparts. The cost of masterwork armor is included in the cost of magic armor." Straight from PHB. What's the difference? Masterwork armor, those such as the Feyleather or Starleather category, have higher bonuses but must for Feyleather be +4 or higher and Starleather +6 or higher. Example: Bloodcut Feyleather +4 ----3(Fey)+4 bonus =7 AC Bloodcut Leather +4 -----2(Leather)+4 bonus=6 AC Both items have the same power, but Feyleather is masterwork with bonus to AC. As for price, I don't know how to determine it. Masterwork are extremely special, and I don't know how the calculation works when take with a base price of a +4 magic item and make it masterwork.