When it comes to the inks used, price increases with the number of colors needed. Printing one color on your tape is cheaper than printing multiple colors in it because of the different processes used. More than one color is passed through the various press, and a separate tape would need to be made.
When it comes to colors, there are specific colors that are in the order you give. Price will apply to attain the color you need if fewer standard colors are to be used.