The Eminence Bow shaft sells anywhere form 750K to 1.5M Adena. The drop rate is not high, but they’re pretty common.
If you are level 30+, you’ll need a group of at least 5. Head out to the eastern part of the Dragon Valley (before Bloody Queens.)
and hunt Succubus Turens. They will drop the part.
12 hours of camping will get 3-4 shafts. Easy Adena!