This is dreadful, over and above the sad circumstances, I know most people really put thier hearts into buying a new car, especially one of the nature of the 350z. Its a worst nightmare case, when you think all is well and then learn you may have been scammed.
Its often hard to spot the bad ones until its virtually too late.
I sincerely hope you manage to track this guy down and then get given 15 minutes in a police interview room with him, so that you can cut his nuts of and staple them to his ears!
I also agree with the above posts, get the police involed, get everyone that is involved, involved, including Ebay - Even if only doing so, helps stop others getting equally scammed in the future.
Best wishes and hoping for a positive outcome