Ayam Cemani are quite rare. They are COMPLETELY black chickens.... black eyes, black feathers, black skin, black toenails, black tongue.... I would poo myself to come across any.
Quality Araucana, Hollands, Houdans, Appenzeller Barthuhner, Blue Hens, Chanteclers, OLD polish, quality dorkings in colors other than silver-gray, flower hens, Jærhøns, java, and orloff to name a few not already named.
Also, I will pitch in for a second and support the Ayam Cemani statement. There's only one or two birds in the US, one of them being part Cemani. There are plenty of Icelandics, Yokohamas, etc. here.
Although I will also agree that true to type/good quality LF Crevecoeurs and Houdans are exceedingly rare, sadly moreso than even La Fleche.