There is no "right" answer in my opinion. Sellers(and buyers) may not price things the same way. The number of "eyes" would certainly be a factor, but not the only one. I would say a $600 2 eye quarter size piece that is a solid color is overpriced....however a single eye half dollar piece that is showing the multiple colors may go for more than $200 or $300.
Price per polyp on something like zoas is much more straightforward. Some of the chalices with multiple colors it is much less straightforward. Even if they may eventually get those other colors there is usually a premium if you can see it in the frag you are buying.