I use skincraft on newgrounds. it is very easy to use and you can save the different layers of the skin in a txt file to change areas you didn't like. it's already updated to the new skins and has useful overlay, multiply and screen layer options.
you should maybe think about offering payment to lure the super advanced artists here, because they might have something better to do than drawing free pictures.
you can get pretty good stuff for 25$ on DeviantART and average stuff for less probably.
hi, i could try to do a picture, but i'd like to know if you, or whoever did the picture, could link me to wherever it was posted first, so i can properly credit the artist.