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
using this platform. it's cool, by the way, mate, any artwork worth checking an/or buying takes lots of time to think through