You could try using Rockauto but using the Austpost shipping address in the USA,
https://shopmate.auspost.com.au/ that way Rockauto is shipping to a US address and the GST is handled by you and Austpost.
Haven't tried it myself but its been around for a number of years now started off for those pplaces that wouldn't ship to Oz before the tax BS came about.
I use a friend in Illinois but it was my second option.