I know Roy, this is the hard part. I did have it in my mind to do another, of course not the same, but the upricing is the difficult part.
As Melissa asked "What would you price it at normally? How many prints do you think the image could have sold over time? Add that up together."
I really have no idea how much prints would sell, since I have not sold much yet. That's a hard one.
Janine, I like what you mentioned. I could easily do that as I don't want to deny him purchasing my original, I too would then have another to sell as prints.
For a pastel drawing that I would probably sell to him for $200 = $250, would adding another $100 seem to low or high? Would prints sell or not? I do not know.
Understand I am only trying to get some advice from others and I respect all who give their advice. Just as hard as pricing your artwork, this is a tricky one I know!