Question about Demonology Warlock Hidden Artifact Appearance

So I was farming the affliction artifact appearance and I figured I'd get the heads while I was at it. I got the 5 first heads and died. When I respawned, I figured it was time for a repair. I jumped on my travelers tundra mammoth and popped into the repair vendor. I have an add-on that automatically sells Grey's. It sold all of my Grey's including the heads, and they are not in the buyback tab. So my question is this: do I need them in my inventory to get the appearance? Or is it enough to have just looted them once? Any help would be appreciated