By the lack of response I assume this is truly an uncommon palm. I thought at least a few people here might grow these... I posted a couple pics below. The first is the actual trees I obtained seeds from. These trees were at about 2500 feet elevation in the Sierra Madre Mountains in western Mexico. The second picture is from a web search, and it shows a perfect mature tree. It is not my picture, ironically it is from a "rare palm seeds" site which does not have, nor ever has had seeds for sale for this species!

I have only grown Cryosophila warscewiczii not nana. Cryosophila warscewiczii is somewhat cold hardy but cant take much wind. They can take into the upper twenty's but no lower and no frost. Not sure if they are similar are not.

I am assuming you want to grow this indoors? Cryosophila species (though as you can guess no experience with this one) are actaully very good house palms- perhaps among the best... very resistant to spider mites and low light situations. Perhaps C nana will be, too.

They look like beautiful trees and definitely deserve to be more commonly sold.

-Alex