I've was checking out on Anime News Network to see if Guilty Crown has been released outside Japan:
http://www.animenewsnetwork.com/encyclopedia/anime.php?id=13001
According to the page above, Madman should have it. But, when I search for it, I only get 2 episodes from their screening room. When I search eBay, I only get Japanese imports and nothing from the United States or the UK.
Has Guilty Crown been released at all on DVD, or is it only available through streaming?
It has been released in the U.S., but I don't think there's any information available regarding the other two countries.
For the US, the show was licensed by Funimation. Wikipedia claims that the anime was planned to be released in 2012, but I'm fairly certain this did not happen. The release seems to have actually happened in August 2013. It's currently listed in Funimation's store in two DVD+Bluray combo packs. Other online stores including Amazon also carry it.
In the UK, the series was licensed by Manga Entertainment. It was listed as "planned for release in April [2013]", but their website still doesn't list the series in their list of titles. As such, it's pretty safe to conclude that no release has been made yet. Their Q2 release schedule also doesn't mention Guilty crown, so it may be delayed or cancelled.
For Australia, as you said the licensing organization is Madman Entertainment. I've looked through their website, but a search for "Guilty Crown" only brings up streams of the first 2 episodes. It is not listed on their release schedule nor on their full catalog. Also, the only news I could find regarding this was an announcement that the series would be streamed, but no announcements of plans for a home release. This suggests that they don't have any plans to do so, and likely have not bought the rights for a home release.
So, as of now, there is only a home video release in the U.S.. It's still quite possible that the UK will have releases of the series in the fairly near future. Australia is less likely to get a release anytime soon.
