The max combined length for a package to Australia is 79". Using heavy, corrugated cardboard to shape a shipping container, You can have a 68" Length, 4" width and 4" depth. Total length plus girth 76". Tape the daylights out of it and you still won't have six pounds. My bows were all in the 60" range, so I used two arrow boxes..end to end..and bubble wrap, and shipped without issue.
The first time I tried the local Post Office they said I couldn't send over 60", so I called the 800 number to the home office of the USPS. I was told there to use the USPS International Rates, and the combined measurements as I have described. Sometimes the local post office people don't know the real rules.
I also list them as sporting equipment, archery item. I've had no trouble. Last one was about three or four months ago.
If you feel awkward about shipping then don't take any bids or money from overseas.