Got mine last night after 15 hours of camping. I was clearing both regrua caves (the two northmost in the block of six), hoping that both Fabled group mobs that spawn there could drop it. I looted 576 regrua claws during the camp and sold them for 100pp each within minutes (they'll take Baking to 288 fairly quickly).
Respawn timer in the caves was roughly 31-32 min.
Edited, Mar 1st 2014 2:47pm by Veludeus