I saw a lot of my friends do this, and I thought it was a great idea! I currently have next to zero points. I have to stock up before Christmas holidays!
It'll be 20 points per sketch, with an added 10 points if you want it coloured. Examples of my sketches here: http://fav.me/d5ojypg http://fav.me/d5njhk4 http://fav.me/d5m4blp
Note: all of the sketches will be busts, unless you specifically want a fullbody, which would be 40 points instead (without colour).