Brad; Contact Ebay for information on seller like his address which you should have for sending him his money, and phone number. Ebay will give it if there is a problem with seller.
If still no contact with seller after that information from Ebay contact his country or city attorney to bring fraud charges agaist him, and depending on the amount you paid it maybe a felony.
If you don't want to do that go to bank and stop payment you can do that even if bank check. If money order sometimes you can have it tracked to find out who cashed it for ID tracking. The faster you do this the better for you.