Not sure when this is ending but Amazon is holding a sale of their ExOfficio underwear range. They don't ship everything to Australia so YMMV.
If you don't know the brand, ExOfficio is known by some as the holy grail of underwear. After living in underwear mediocrity for decades, I stumbled upon them 4 years ago and have never looked back.
I bought a few pairs of these a few years ago and never looked back, I will not wear anything other undies while backpacking now. Simply the best when it's hot and sweaty, good gear is worth the price.
They really do dry super quick too.