Using the GSP is actually not a bad idea if your buyer is ok with it. That being said, they can still file a claim even if you go that route. I don’t think you’d be more protected than by using Paypal G&S tbh.
Obviously as a seller, the best way would be receiving Friends and Family payment, but I don’t know many buyers willing to blindly send $6,000 to a random person.
The safest method would be using a middleman. I don’t know if we have a trust worthy member from New Zealand that could help you guys.
OP, the first thing you should do is ask the buyer if they’re ok paying customs. That will be $900+ so before you waste any time, just double check. I had some random buyer from Norway ask me to declare $3000 worth of cards as a 25 euros gift. lol
You need to make sure you can get signature confirmation. If you don’t get that and just get normal tracking it will show it has been delivered to Australia but it will never show delivered to the individual. So if they want to scam you they can say they never got it when in fact they did.
eBay GSP is the safest (for the seller) most expensive way (for the buyer) and I couldn’t recommend it more.
Paypal goods and services is solid as well but make sure you are using a shipping method guaranteed to have a signature at the end of the line. Go to UPS, Fedex, USPS and ask them what services if any can provide that guarantee. Without confirmation of delivery with their signature you would be in a very bad place if a claim were to come out of it.
Another thing… If you go the GSP route, open a ebay store. It will cost you something like $25 for one month but you only pay $250 max fees instead of $600+ on a $6k item.