The guy melsteve is talking about is indeed the only one who can legally collect Leafy Sea Dragons. Australia is doing a heck of a job protecting them!
He collects 1 gravid male per year and returns it to the ocean once the fry have been born. Then he raises the fry - has to go to the ocean every single day to collect 'pods to feed them. Once the fry have grown up, they are sold to public aquariums for $10,000 a piece (from what I have heard, there is a waiting list for them). He does not sell to hobbyists at all; as far as I know, the only non-aquarium that has been able to purchase some from him is Ocean Rider Seahorse Farm, and even then, it was only after an aquarium's purchase fell through at the last minute. They had spent several years trying to persuade him to let them buy a pair by then, and if it weren't for that deal falling through, I doubt they would have ever obtained any.
My point is that, like Steve said, your best bet is public aquariums. Even so, it would take a miracle for you to get your hands on one.
Sorry to disappoint you, but if you want sea dragons, the only ones a hobbyist can realistically hope to get are Weedy Sea Dragons (though they are just about as difficult to obtain).
tl;dr - You really have no chance of getting them straight from the source, so public aquariums are your best bet, but even then your chances are almost nil, and it would cost you an arm and a leg.
