Well, it really depends on what the person requests from you. If it'll be traditional art, it's considered cheaper than digital art; since digital is a tad harder than traditional styles (though that's just a popular opinion from most artists).

And it's also based on if that person wants it coloured or not. I honestly don't know since I don't sell my art. ^^ Maybe you should look around the other art shops around here? It'll give you a basic idea on how to price everything. :)

I hope this helps! :D

In my opinion it depends on what your doing but I'd probably pay 5k but that might be a little cheap...maybe 10k