Dragon Eyes are also Very Common.... I guess I do live in an area saturated with nice corals so it's all pretty common around here.
Here is my theory on named zoas and "rareness" If it has a name, that would most likely indicate that enough people have them that someone felt it needed a name. Wich means they aren't rare or uncommon. I can't really think of any zoas thare are really that uncommon, they may be in a certain area, but there is always the interweb.....
Even the infamous PPE isn't even what I would consider uncommon. The truly rare or uncommon zoas are the ones that are NOT posted on here or other sites, not talked about and not widely fragged and shared.