If this is correct (straight from the BBTS website)
USPS Air Mail $36.99
Usually arrives in 7 to 20 days - not trackable. Contact local customs office for duty and tax information.
USPS Express Mail $47.99
Usually arrives in 5 to 8 business days - trackable. Contact local customs office for duty and tax information.
UPS AIR SERVICE $55.99
Usually arrives in 3 to 5 business days - trackable. There are no duties or taxes if order is under $1000 AUD.