I've never liked the Big Day Out 'festival' but this possibly makes it worth checking at least once.
http://bigdayout.com/news/index.php?NewsId=15
27th January (Sydney) - two people can get in per one ticket. ie half price entry.
http://bigdayout.com/news/index.php?NewsId=15
27th January (Sydney) - two people can get in per one ticket. ie half price entry.