I've been scammed by a buyer?

[moto288]

I've sold something on ebay in early December. Sent to the buyer (2 feedbacks). I spent some time to proactively chase up postal service on a delivery delay and had it delivered on time. Buyer was impressed with my correspondence and left a good feedback for me.

Fast forward to after Christmas, buyer suddenly filed a return citing the items I sold weren't authentic (but no email correspondences). But they are, because I've bought the item myself from the brand boutique. Having read stories here about buyer scammers, I'd rather have my items back than lose it and the money. So I asked the buyer to 1) authenticate it at their boutique, 2) show me photos showing the differences they claim there is between my item and their "original", 3) find out the cost of postage, send the item back to me and I'll reimburse postage. Buyer was barely engaging with me. He never provided any photographic evidence that I've requested and insisted I provide a shipping label (I cannot provide a US international shipping label from Australia - USPS would not allow me to order one online as I don't live in the US).

Given I could hardly get the buyer to cooperate to have the item sent back to me, I escalated the case for eBay to step in. Originally they had the case on hold until 4th Jan to receive any evidence from the buyer. But today they've extended the deadline to 8th Jan.

I'm worried that eBay is stringing me along indefinitely, as they seem dragging this on when they've given me a deadline already and would suddenly change that deadline. I am also suspicious of the buyer as:

1) The buyer wasn't able to provide me the photos showing the differences he mentioned in his allegation

2) The buyer didn't cooperate to get the items sent back to me when I ask him to, I had to send him messages 2 days in a row before he replies. If he really think my item is not authentic, he wouldn't wait to have it sent back and get his money back asap.

3) There's only 2 feedbacks for the buyer, which in hindsight is a bit worrying now.

4) My photos in the auction have show the markings that he claim is not authentic. He would've checked it before he bought it in the first place.

I suspect the buyer is either a fraud, or wanting a return because of buyers remorse. But I'm worried ebay only sides with the buyer and in the end I lose both the item and the money. It's a high value item (over $1000).