Binding Powder  

 

The Lizard casters in Temple of Cazic Thule (justicar/judicator/lifedrinker/lifestealer etc) have a fairly good drop rate on this.
I camped the throne room area for the clicky levitate shield for maybe 7 to 8 hours , and managed to gather 60-70 powders as a lvl 60 cleric duoing with a 58 SK and 2 mercs , so we were killing at a slow rate (they have a nice amount of hp though...).

It should be a decent spot for any 80+ player.