Tell me you've never bought anything from Sears, K-Mart, Walmart, General Motors, Ford, Chrysler, whatever,
and not had something go wrong. Even the United States Postal Sevice screws up. ( Don't ask me how I know!)
The odds aren't any worse. And, you do have recourses through e-bay and PayPal, to get the problem corrected.

NOTHING is guarenteed.