Here is a good way to make your own watercolor paint.  This will make a good substitute to commercially available watercolor paint.

 
What you need:

1 tablespoon (tbsp) white or cider vinegar

2 tbsp baking powder

1 tbsp corn flour

½ tbsp glycerin

2 drops food coloring

1 teaspoon water

 

What you will do:
  1. Mix the vinegar and baking powder in a small bowl.
  2. Add the corn flour and glycerin when the baking powder stops foaming.
  3. Stir in the food coloring and add water if the solution seems to stiff.
  4. Store in a tightly covered jam jar or plastic container.

 

Source:

►Make your own homemade Watercolor paints. http://www.makeyourown.net/water-color_paints.shtml