This is why I never buy used gear online without some sort of intermediary agency, such as eBay or Reverb. In those cases, if you wind up dealing with a "bad actor", the company in the middle can (usually!) sort things out.
-- Lugia
It's a good practice. That's why I like the thread where you can leave feedback on people with GOOD trading habits. I spent over $500 getting two modules built by a guy on this site. I left positive feedback and would recommend him to others.