Nevertheless, lodge a police report, report to eBay and set an
ultimatum of deadline. No response by the due date/time set,
initiate your next logical action.
Obviously, you are in the wrong in the first place by not abiding
to eBay's terms and conditions of conducting auction. So, expect to
write off the item you sent if all fails. It is classified as
internet fraud, but sadly with your knowledge to do so because of
your shortcut in getting payment. Ever heard of Cash-On-Delivery or
PayPal? Use them in future.
I do not see any issue at all since it is between the buyer and the
seller in a commercial transaction bounded by eBay's terms and
conditions.