[Mysticism] Where to get the regs?

[Picus at the office]

I can spot where to get most of the regs for this skill but what about Daemon bone? If I wanted to carry 40 of these do I have to go to doom and farm? Is there another spot or way to buy these? I've tried to search but have had little luck so can anyone lend a hand on this?

 

[Petra Fyde]

All of the void creatures except korpre and ortanord carry daemon bones as loot,.

 

[Picus at the office]

But there is no purchase option? Yikes.