I couldn't tell you how long it takes someone who does people all the time. I can only say that anatomy is not easy. If you go through his work, and he's extremely good, you can find errors. I am not good at doing people and I haven't practiced them much at all. All I can say is if I was doing an animal I would guess 4-6 hours. Since it is more of an illustration than realistic because it's mainly the lines you are linking us to it might be faster than that. Fully painted, probably longer. I have never really done that style but with practice you could speed that up I'm sure.

If you look at the Bluebird in my deviantArt link of my sig, that took me about 5 hours. I'm just an amateur though so bear that in mind.

As far as pricing goes, that's all over the board. I was looking at someone the other day on dA who does character portraits and I think the price range depended on how much detail there was. I think 20-50 bucks but don't quote me. Also, I think 20-50 bucks for what you linked would be rather underpaid. That's just my opinion but someone who can whip one out in an hour would find that acceptable I imagine. I just know I can't do it in an hour. I think that person on dA said they make 20-30 bucks an hour so you get what you pay for.

Those are my thoughts but maybe someone who does more character work can answer in better detail.

On a final note, it's worth remembering this is a Cartography guild and most folks here do more maps. You might get better feedback on a site catering to character and monster art.