If you are decent at washing the shell, cutting along the lines, placing window masks in place, spraying the paint, and applying the decals, then you should end up with a respectable shell. There is no shame in driving a one color car. If however you are unable to do that, you can still find someone that can do it for you.
You can always find painted shells on eBay. Just search for the HPI part number for the shell and add the words custom and or painted. You will still have to punch holes for your body posts.
www.battlefieldraceway.com Racing videos at http://www.youtube.com/snoopyrc