Jokes aside, I think it's really all about setting a limit in this (or any) hobby. Do you really wanna spend more than a thousand dollars on a small little action figure that's just standing on a shelf, collection dust basically?
For me personally the answer is no. Just like niekgrijz said. It's kinda hard to justify.
But I'm not saying it's wrong to do that. Most people would probably say that I spend way too much on this hobby as is. But do I care about that? No, not really
If you wanna make a living from making custom figures alone you have to charge prices like that. I get that. So I'm not trying to criticise either.
It's just all about personal choices, I guess...
I try to think of it as art, like a 3D painting, it helps me sleep at night