Didn't you think to tell us what the latest estimated delivery date was when you bought it? That's what counts on eBay.
Unless it was being delivered by surface mail I imagine it's well overdue for delivery now. If so, you can use eBay's money back guarantee. A case must be opened within 30 days after the latest estimated delivery date, so you may need to act quickly. If the matter hasn't been resolved 8 days after opening a case the option will appear to escalate it for eBay to step in. The seller will be required to provide eBay with tracking evidence of successful delivery to your address. If they can't, eBay will enforce a full refund.
Have you told the seller what's happened? They must have posted it over a month ago, so they will need to know what's happened. Is it possible that the item was subject to any US export restrictions, or prohibited for transportation?
