Despite the advice and opinions given to you above... lots of which comes from very experienced and knowledgeable sellers by the way...

Nonetheless, if you still firmly believe you have been scammed by either your buyer or ebay complicity (or both) and you have strong evidence to back up your claims then I would encourage you to raise a formal complaint with The ACORN.

http://www.acorn.gov.au/

Present your case, including of course your evidence, and allow the Federal Police to investigate it.

Then inform ebay of the case reference number. They may even reverse their original decision if they can see you have strong evidence that could in some way make them complicit.