Yep - we had one yesterday which weighed 660g from Hobart to WA. It was actually cheaper to split it into two parcels of 330g ($13.20 v $17.95 - and only $19.90 to send them both Express Post).

Just one of those things with the regulatory requirements on Australia Post re letters and small parcels.

On one hand ... it's crazy that it costs me the same to post a 330g parcel from Hobart to Darwin as it does to have it posted to someone with a PO box at the same Post Office that I lodge at.

On the other hand it is fantastic that I can get the item delivered to Darwin at no extra cost, and that I have that degree of predictability with 98% of what I sell.

It just goes to show that it is worth taking the (very small amount of) time needed to understand postage rates.