According to this, the seller is responsible for getting the item to the buyer. That means if it gets lost in transit they must reimburse you and pursue their carrier for the loss.

I had an item take about 3 months to get to me, and the buyer had offered to reimburse only half the price. That's when I checked out the seller's obligations when it came to ebay sales. It did finally arrive, thankfully, however the time to leave positive feedback (for the seller's patience) had expired after 2 months on ebay.

Anyway as others have said, if you have no joy with the seller you can lodge a dispute through either ebay and/or paypal to recover the money. If a seller is shirking their obligations as per ebay policy/rules then you can report them.

Best of luck! I hope things work out for you.