I let them into my house and I was alone. From now on anyone who enters my home and I don't know, I will have a piece in my back pocket, cocked and loaded!
Jay, it's better simply NOT to let anyone in your house under those kind of circumstances (i.e., unknown buyer you connected with through the classified/internet). It's a COMMON robbery scheme....and having a piece "in your back pocket" might FEEL comforting--but there's no guarantee you're gonna come out ahead in that kind of situation, and once a gun gets involved it gets pretty likely that SOMEBODY is gonna get killed (don't talk to me about gun rights--I'm MR gun rights, I've been shooting for over 50 years...and I once held a guy at gun point who broke into my house).
For a car, it would be better to meet the guy IN THE YARD--in public. If it has to be in the house, have a friend come over (and have the piece, too).
A LOT OF PEOPLE have been robbed (or worse) in those kind of situations. Furthermore, when a guy starts getting older, he starts LOOKING like a good victim--even if he really isn't. If sh** starts to happen, older guys seem to have a tendency to get hurt....