I have not sold graphic  here for a LOOONG time. 
- 

Curious what my image might range. 
Please keep in mind - these horse images are picture I took using my cell phone - so the quality is not as good as some other stock sites would be.

I have 2 ref images right now 
https://horsephenomena.com/horses.php?id=464591
https://horsephenomena.com/horses.php?id=464590

I price my graphics based on highest bids in auctions. You have talent and I would play at least 50mill for what you have. So maybe make a premade and toss it in the auctions with a starting bid at the lowest you would take for it and no autobuy? Whatever your premades sell for you can add a little extra to that price for your customs.

I agree 40-50 mil sounds reasonable for what you can do ! I'd def pay that !

I agree!