As a hobby, I collect cast iron cookware. In the last year or so, I have bought items from an online auctioneer.
Most sellers are aboveboard.
However, the anonymity of the Internet encourages deadbeats to become part of the process. Also, you may want to alert the auction site about the matter to see whether de-listing the fraudulent seller is appropriate. Magazines, newspapers from around the world and trivia can be found almost instantly. Living online was one big research project. I turned up information using search engines and at times by just taking wild guesses.