Old Dan,
The last several packages I have sent to Australia didn't need customs forms.
I send the packages first class mail, and it isn't very expensive. I think the coins I just mailed to tiddyathome only cost something like $3 to mail. I have probably mailed a couple dozen packages to Australia, none insured, and I think all got there.
There was somewhat of a mystery recently where I sent several packages (or thought I did) to Australia. Humpybong and GregK never received theirs. However, now that I look at the piles of coins on my desk, I wonder if I really mailed them. That's another story, but let's just say there's a good chance that none of my packages ever disappeared.
So, to sum up. No customs form needed. First class mail. No insurance, and your odds the package will arrive safely is about 99 percent!