Let's say it took him less than a week to sculpt and paint up (I don't know if that's generous), you'd pay for a custom, one of a kind piece of art by someone who is one of the best in his field at a rate of $20-$50 a day?
Yes thats all its worth to me, if its a one off or mass produced its irrelevant for my perceived value of a 1/6 head but I gave myself some leeway considering its custom and came up with $100 (obviously Im not the target consumer).