Cartoonist Dustin Harbin has an on-going offer to take commissions for sketches of just about any subject drawn in an hour for thirty dollars. You can see a wide-range of his work on his Flickr gallery. He uses black ink and a 7" x 8.5" piece of Strathmore 500 bristol.
Castle Of The Great Tree
Little Dreams, Big Bookcase
It's Easy To Get Carried Away With Your Legos