Palmer standard colors, 2oz, $1.85
Logical buying criteria:
Containers per painter = Number of hours * number of paintings per hour / paintings per container
( 3 * less than 20 ) / more than 20 = less than 3 = 1-3 bottles per painter
Therefore one bottle of each color for each painter will well more than suffice.
Red
Blue
Turquise
Green
Purple
Pink
Magenta
Orange
Yellow
Brown
Black
White