As at today's exchange rate: $99.oo USD = $131.6o AUD. This would be plus postage, of course. There should be no added tax or GST as long as you stay under the $1000.oo AUD limit.
As far as US postage is concerned: I believe the USPS charge their parcel rates by weight and level of service: i.e. how fast they get it to you. Link to the USPS is here:
http://postcalc.usps.gov/
example: A 1.0 kg Airmail parcel post (4-10 days delivery to Oz) = $25.80 USD
Same thing weighing only 300g = $16.oo USD
Ditto 3.0kg = $45.85
Bearing in mind that these Burgess Planetary eps weigh in at 6oz/227g each.
There are cheaper (surface mail) options, and much more expensive express options also. I have found 10 -14 days to be average for airmail parcels.Hope this helps your calculations
This is looking better all the time.
I would also like to get my hands on a 6mm of the new production run. If it takes a little while, then I don't mind, as I can save the pennies in anticipation.
Dave