Did you pay with Paypal? Did you fund the payment with a credit card? Did you read the rules of trading on eBay and/or payinmg with Paypal? Or did you just tick the box?
A short history of online buying through ebay and paying with Paypal, as relevant to Australian purchases -
You buy. You pay. If you don't get the item within 45 days, you open a dispute for item not received with Paypal. The seller then has the opportunity to provide Paypal with proof they posted your item. If no adequate response you escalate to a claim with Paypal within 20 days of opening the dispute. Paypal then decide.
Did you do any of these steps?
I'm thinking not, in which case you might be able to leave negative feedback, but you have probably kissed your money goodbye.
Somebody with your supposed experience should not be falling for this type of scam
