If the item is stopped at customs, a PayPal claim might not be successful, but I suspect an ebay claim could be.
It's true that there are some obvious warning signs to look out for that can indicate an item might ship from outside AU, and it's true that knowing what they are can mean you'll avoid them, but none of that detracts from the main issue - the seller (if indeed the item does ship from outside AU) blatantly lied.
It's no different from a seller deliberately misdecribing other aspects of an item and causing problems. Besides which, it is eBay policy for a seller to be aware of the import regulations of the countries they ship to, and to not list items for sale to countries where the items are prohibited for import, so if it causes problems at customs, the seller has breached more than one policy and I tend to think eBay may be inclined to look favourably on a buyer in that case, if you contact them directly and explain the situation properly. (eBay do not usually require buyers to return items if the return address is in a different location than stated in the listing, so they already make provisions and exceptions for buyers who get caught out by this practice).
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