and then there are the flat rate boxes, which are great value for heavier items having a fixed limited of 15 kg.

Due to a small Australia Post glitch that they promise will be fixed soon, prices for the Flat Rate Postage boxes are not available online.

These flat rate postage prices are:
BX1 - $6.50
BX2 - $10.50
BX4 - $13.25

Tracking with Signature, is an additional $1.00.
(When you select this option, this makes the article a signature service and you are covered for up to $100 for loss or damage).

plus the cost of the box

$1.75

$2.35

$3.10