Seriously, what information do you have on the seller? Name, address, city or phone number ( if the seller is using a burner, no traceable)
The computer is a very useful tool in finding and finding out about people. Criminal record, Sex offender, out standing debt....
Years ago a CABEr had somewhat the same situation, except the CABEr was the seller and the buyer was the person in question. The bike got shipped and the perp retracted the the payment.
With some information, I found the address, phone number of the buyer. With Zillow I got a street view shot of the house. I posted it, with said information, but it was taken down. Never did find out the end result...
I'm not saying , found out where he or she lives and do bodily harm, or take photographs of his or her children or make threats....and so on. It will give you the type of seller you are dealing with. If the address is a vacant lot or abandoned house....
Anyway...I hope you things work out and you get your bike.