Since some of the people here are vary bad at image editing (me included) we've set up an Sprite Request board in these Forums for anyone who wants a sprite made but can't do it themselves.
Post your request there, and the people who are good at doing them, will do it, if they're available. Please be patient since some of them may be very busy with other sprites and life in general so they may take a while.
If possible, add link to images of said character and other specific details you think may be important.
Since every case is unique, in some of them the person handling your request will contact you if they require more information.