Just send them as parcels. I think customs fees only apply to things over 500g or thereabouts, so you should be fine with anything under that. If in doubt, you can just state it in your listing like alot of sellers do.

I rarely send overseas but haven't had any of my parcels go missing. Aslong as you register them to be eligable for SP, all should be good. If anything, it may mean an Aussie buyer wins at a higher cost because they got into a bidding war with a buyer from overseas.