My own practice, when dealing with values over $200, whether buying or selling, is not to have either the cash or the item.
Once I've made contact and determined that I want to move forward, I call the wife and she arrives in her car with the item/cash. She is also carrying, in case things still go bad after all that.
I go to my credit union. I was selling a car for cash and went to my credit union and did the transaction in the lobby with the CU’s blessing. They even came out and helped us with the paperwork.
Smaller transactions? Still in the lobby of the credit union. Once in the lobby of our postoffice in front of the cameras.