Thanks for the links, when I see the catalogues I want to move to Australia!! I love the Aussie Dens as well, but those are extremely difficult to find here as well, I only know of one UK grower who has some every few years.
So far my best bets are the 1st and 3rd places you list, the other 2 either don't have flasks or ask a $500 minimum order for overseas. Might be the case for the other 2 as well, but I'll have to email. Hope not, that way I can order lots of little flasks in the spring!
I'm thinking that this would be a perfect excuse to go visit my australian cousins!