I've realized that I have no clue what people want to pay for commissions and I want your feedback on how much a fully shaded piece of mine should fairly cost.

The first time I opened for commission back when my account was teeny tiny the base was $10 plus half that per extra characters. That was a mistake all three of my rotating slots were filled instantly and never became open again since I was dealing with the backlog and when I was done with that I was just done in general.

Recently I've had a few situation that showed I just have zero clue what a commission is worth so I figured that the only good and fair way would be to ask you guys:

So for a fully shaded pic should it be?
-$30 plus $15 per extra character
-$40 plus $20 per extra character
-$50 plus $25 per extra character
-I'm completely wrong and it's not anything in that range.

I'll base my flat, background, comic, etc on the shaded pic price.