I just purchased a 160 twin engine froma guy in the US. No problem. Have a look at the feedback for the seller and make up your mind. I have got a lot of stuff from here and also Ebay without being cheated YET.!!.
I get a lot of stuff from Tower Hobbies and also BVM.
Australian customs don't charge any duty (tax) on articles with a A$ value of less tahn $500. So I try to keep the parcels less than 500.

Regards

Don't be tempted to use surface mail, it takes forever. USPS has a really good airmail service.