[Buzz]

Greg, CMYK is a 4 color process using screened mixtures of base colors cyan, yellow, magenta and black to achieve a near full color effect. Simulated process uses (I think) 7 screens to produce a superior, near photographic screen printing effect, but basically the more screens (colors) you use, the higher the cost of production. Single color designs are the cheapest, followed by solid spot colors, with each additional spot color adding to the cost. once you get past 3 spot colors, you might as well go to 4 color process for a near full color appearance using 4 screens. I mostly produce designs, so folks in the actual printing business may chime in with clarification or corrections.
The number of colors you decide to go with based on cost or desired appearance of the finished product will influence the design.