Outside of cash, a wire transfer is the safest for the seller. Set it up so that you can call your bank to initiate the transfer once you see the game.

I just sold my very nice MM, and the seller brought cash.

Also, I just bought a game with Paypal (close to 4K). I was a little surprised as Paypal is not guaranteed. An unscrupulous buyer can later challenge the transaction. But I am an honest guy and the seller trusted me. I also picked up the fees. (Why should the seller be stuck with fees when he/she can sell it for cash)
There were fees because I paid with a credit card. I was going to wait on my bonus from work to buy a game I wanted, but a good deal came up 2 weeks before my bonus, so I charged it and then paid it off 2 weeks later when I got my bonus.

I haven't worried much about this since when buying a pin you ask specific questions that only another pinball owner would know.
For example, you ask about wear, condition of cabinet, plastics. You also ask for pictures. Also, you are typically meeting at the persons home. (Not always though)
I can see smaller ticket items being much more of a target for scammers. iPads, jewelry, etc..

I don't recall someone being outright robbed during a pin purchase. You do hear of people getting ripped off when buying a pin remotely. Typically this is, the condition was not as advertised.