Buyer hasn't paid, but has item

[joslight]

Long story short. Mistakenly shipped item to winning bidder before actually receiving payment. Bidder is now in possession of said item, but has refused to respond to my messages requesting payment. Even said I'd pay all return shipping costs if he can't pay the bid amount.  I've contacted ebay, but they were zero help. Basically just told me to file a claim with them.

Also, the buyer has a lot of negative feedback calling him a scammer that doesn't pay, but it's all marked as positive. How is that possible?