Havanas are so pretty! I like their chocolate coloring, too.
I think they are fairly rare. There are a few other breeds that have chocolate coats. Burmese and Tonkinese come in a darker version, sable, and a lighter version closer to the chocolate, champagne solid. They are very different cats from Havanas, though... stockier and more rounded.
Sorry but like Gadiva says, they are uncommon and not a lot of breeders of Havanas are in the US. You'll have to do a google search to locate any breeders. And be prepared to deal long distance from where you are. You might have to find a kitten more from emails and phone conversations then to actually see the cats in person.
I rarely saw them in the shows and I showed over 25 years.
Wow! They are beautiful. I just googled the name and seen some lovely pics. The Fanciers Breeder Referal List said they are so rare that they are considered endangered. And there is thought to be fewer than 1000 in existence.