Postgraduate programs in Australia?

Hi, I am an American undergraduate student looking to earn my PhD in Australia. I attend an extremely selective university (ivy league,) but my grades have not been stellar. I have received mostly B's with a few A's sprinkled. I will soon be entering my senior year and need to make plans after college. Currently I am looking to live in either Sydney or Melbourne, and have been looking at schools like UNSW, as well as others like it. My question is, for those of you who know more about Australian schools, do you think that I'd have a good shot at being accepted to a PhD program in psychology? Any advice you have would be great. Thanks so much!