You could try giving Four Winds Growers an email and I'm sure they could get ahold of one for you. They do not officially sell that variety but can make special orders. They are based out of California and would probably be the quickest option. Four Winds generally will give you a high quality tree (and fantastic customer service) but it will not come cheap.
http://www.fourwindsgrowers.com/
Another option would be to get ahold of the owner of this site (Lazz) via PM (private message) and see if he can bud you one up. That's what I did! He has some other options currently available here:
link
I tried getting ahold of a Nules for a while and pretty much the only other option is Tree Source which would mean that you would have to by a minimum number of trees if (I'm not mistaken) and it seems as though anyone who does buisness with them is disappointed.
Joe