Doesnt it drop from RB aswell, even if they are 75+
Well yes, a couple of 78+ level Raid bosses drop it in C4 as well as the two big dragons Antharas and Valakas....but I figured if the OP didn't know what GRADE the armor was, there was no point in adding that info, as by the time C5 hits this is likely to be changed to the new 'orb system' and thus irrelevant.
Yes, farm 2billion silenos or orcs in Goddard, for a chance to get the recipe you want.. best bet to get it cheap is to farm the recipes for helmet, boots and gloves, and buy the armor since it requires a ton more quest items.