It's been a while since i've asked for a general price range that makes sense for my art. SO based upon this drawing what would you pay, or just thoughts in general of it.
It depends on how much effort you put into it (imho) in addition to the quality of your work (which is fairly high.)
If you're only selling sketches, then I think $20-$30 is fair, but judging from your style and knowledge of anatomy I'd say $50 for something more cleaned up. Colored should be higher than $50. Don't go below that because people take advantage of artists so quickly.
I had an illustration gig that lasted a year, and I regret not raising my fees. It makes me wish there was some sort of US art committee that created guidelines for artists. "You must pay enough for the artist to have more than a happy meal dinner"