I was actually just about to make another post to this thread since I just happened to run across a person very near me, roughly 30 min from here, who has a pair of cassowaries. Her name is Mary Lee Stropes, and she was really well-known in the ratite community, especially with rhea farmers, back in the early 90s. She acquired her pair from a breeder in CA, who evidently produces a number of birds or at least has produced many. She got them as adults in 2000, and has gotten eggs from them each year, but hasn't had any luck with hatching yet. She has a website, though not cassowary-oriented, at
http://www.capybaras.org . She does ship animals, so if she ever gets any produced, she'll probably be willing to ship them off.
As for my comments on their aggression, I was going on what I've read and seen on TV. Now, after speaking with Mary Lee, I can further confirm that some, probably even most, cassowaries are extremely aggressive by nature. In her words, "that female will eat your lunch"...lol. Of course, there are individuals within each species and a high degree of variation between temperaments, but the fact that they have been known to attack at kill people with very little to no provocation warrants them the utmost of respect. According to that husbandry site I listed earlier in this thread, they've been known to even jump fences to go after other cassowaries or people. My suggestion if you ever keep them would be a high, at least 6', inner fence, surrounding by a second exterior fence, just incase. Also, some people have successfully removed the claws from their emus, rheas, and ostriches to make them safer to deal with (though I can only really see this being necessary for ostriches), so it should be possible to remove that inner toe spike from the cassowaries. This would best be done at an early age, before the birds are big enough to pose much of a risk in handling. I'm in no way recommending this be done, so don't jump my case about it..lol..but it's an option.
I'm planning to go visit Mary Lee this Sunday to see her menagerie, and will get to see the cassowaries and you can bet your rear I'll be taking tons of photos. I'll add another post to this with pictures that I take.