Ask Mr. Smarty Plants

We're very flattered that you came (via Internet) all the way to us in Austin, TX in search of a solution. However, the Lady Bird Johnson Wildflower Center is dedicated to the use, care and propagation of plants native not only to North America but to the area in which they are being grown. So, we would not  be able to recommend that it be grown in Australia, which already has some problems with imported North American plants becoming invasive. However, there is an even more important reason why we would be unable to provide you with a source for this plant. It is native to the southeastern states of the United States, and considered endangered, threatened, of concern or extirpated in every state in which it is native. In fact, it does not even appear in our Native Plant Database, which is really a shock to us.  If it is being cultivated anywhere in the United States, it would be as an attempt to re-establish it in its native environment, and not for distribution elsewhere. These two websites can give you some more information, but we think it highly unlikely you are going to find a source for either the berries or the root stock. 

Kentucky State Nature Preserves Commission

USDA Plant Profile for Berberis canadensis