Sorry to say Daydream but if the parcel doesn't turn up yes you will have to refund the seller. Even for samll parcels click and send is the best way to go, they have a 500g satchel $6.20 (I think) and a 3kg for $10.55 and these can be posted all over Australia. So long as you lodge at the PO you will least have proof of sending should a buyer open an INR dispute