You seem to know it all, so this is probably going to be disregarded -

Keep a note of the address; revenge buyers are unlikely to have multiple addresses available. Then cancel if they buy. If they continue to do it (unlikely in most cases) report them to eBay for circumventing blocks. That used to work eventually. I'm not sure if it still does.

Why are you posting on eBay USA anyway? You are Australian, listing on eBay Australia. The rules are different in the USA.