I have had the "skeleton" (the black and white version) of the seahorse created now for about 5 months. I recently decided to color it just to separate the subject from the background better. I think it was really beneficial. Also, I've had a lot of great response from it.
If someone wished to buy the colored print, I would create a special color scheme for them that I would not reproduce. So my plan is to sell the black and white colored print for $50 and the colored prints for $100, since they are unique and original color.
This took roughly 2-3 hours to color, whereas the skeleton took around 25 hours to draw. I used micron pens for the black and white, then sharpie and prismacolor markers to fill in the color. Again, this is just one version of color. I would actually like to see it more blue rather than orange.
For my website, I posted the skeleton against the colored drawing.
Black and White against the Colored Print