Sunfish,
The ELT you are looking at would be available on-line through Aircraft Spruce at around $600 so GST is not payable. Shipping via USPS is way cheaper than UPS or FEDEX.
If you import one from the USA you need to order it pre-programmed to the AU code:
406 ELT's are serialised with a binary code to identify CAR 47 information: i.e Country of registration and aircraft details such as model and registration number.