When I bought the scooby it was from a guy eho lived in a city, from the start he was twitchy and told me it was locked up in a place with CCTV. He was very cautious, he had also had the full range of spam calls.
I paypaled him a small deposit as I was away for two weeks. I also directed him to this place. So he now had some sort of reference and my address.
After that it went smoothly and i paid cash at his house. The monet didnt appear until we were both happy and it was all done very formally but efficiently.
Handing the money over in a bank would seem to work very well for me but at the end of the day there needs to be some trust.
There are always a few ways to get a little idea of the seller in this internet era.