Art is always worth what someone else is willing to pay for it. I was not able to locate original signed artwork by this artist for sale online, however, prints of his drawings are for sale on Crow's Shadow Institute of Arts website. They range in price from $800 - $1400 USD. Their website is http://www.crowsshadow.org/artists/show/18.
You can take the pencil to a stationery store and they will be able to give you a range of the value for the pencil. The value may differ on the market price right now but you can get a good deal out of it.