I dont think so. I do know GST can be a problem, Your postage, Packaging and any other expenses you must hold receipts so when you buy your envelopes, bubblewrap, tape etc make sure you keep your receipt. Now FVF on eBay for item sold including postage they DO NOT include an ABN Number.. so that is a no go.. I have read somewhere when you lodge an item with AP they can supply a recipte but  they do not give a receipt with tracking from C&S for parcel post. So I would be very careful... GST almost cost me my house and assets 5 years ago