there's no fixed price for that kind of products just because it's hard to evaluate. that's why the auction is the most suitable way of selling them.
More than that, hand-drawn cryptocurrency themed artworks are pretty rare. I saw that something has been sold at ModulTrade marketplace about a month ago. Won't send any links, just google if interested. Probably they have something more, who knows
How long I've wished this topic to come
Didn't find any pieces of art there. Looks like it was a one-time event, but will check it from time to time