I would say they are pretty rare. However, I think what is more likely is that you fell in love with "medium/large conures" because they all have similar temperaments. Some examples of these kinds of conures would be: Sun, Jenday, Nanday, Queen of Bavaria, Blue Crown and Cherry Headed. The ones I am excluding from this specifically are Green Cheeks because they have a different temperament than the medium conures.
To elaborate on this (because I love adding genealogical trivia, as it give me the excuse to learn more myself!)...
Sun, Jenday, Nanday, Sulphur breasted, Gold Capped, Queen of Bavaria, Blue Crown, Cherry Headed, Brown Throated, Dusky Headed, Orange Fronted, Mitred, and Peach-fronted Conures are all Aratinga Conures, commonly referred to as Large Conures. They are relatively similar in temperament and size, generally louder than Small Conures.
Pyrrhura Conures, commonly referred to as Small Conures, include Green Cheek, Black Capped, Blue Throated, Crimson Bellied, Maroon Bellied, and many many more. Green Cheeks are the most common of these, but there are many color variations of Green Cheeks, some that are quite rare. Green Cheeks tend to be smaller, less loud, and otherwise fairly similar in temperament.
In MY opinion, Conures are WONDERFUL!!!!!!!!!!! You can't go wrong with any of them. Pick one that looks pretty to you, but most importantly, pick the bird that picks YOU. When you find a parrot that seems to instantly like you and wants to be with you, you've found the right parrot for you.
