Your basic pigments in the printed color chart will not be more than 5, 6 or 7. Most commercial cards exceed that number already.
A good RAL swatch guide of car paints, house paints or offset or silkscreen ink catalog swatches or artists acrylic paint swatch books have more pigment samples. A good UV enabled and a UV cut spectrometer to measure the colors is a next step and allows you to see whether the pigments actually differ in their spectral plots, you might be able to see whether the orange sample is a genuine pigment or based on a mix of yellow and warm red. It is also a good thing to keep fade properties of the patches in view, both pigment and original paint medium + the substrate characteristics: does it contain OBAs, is the paper or plastic shifting color in time. The surface should be matte or satin at most. Sericol or Marabu silkscreen basic mixing ink swatches exist, I think the pigment number can be up to 10.
Met vriendelijke groet, Ernst
340+ paper white spectral plots:http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
update april 2012: Harman by Hahnemühle, Innova IFA45 and more