I was a longtime lurker before I began posting, I spent a lot of time educating myself in all aspects of the pinball life. One of first lessons I learned and which has stuck with me since was from Vid's guide. For the best protection as a buyer and seller, an online escrow service is the best. One company he mentioned was escrow.com. Makes sense. Basically, no money changes hands until all parties are satisfied.
https://pinside.com/pinball/forum/topic/how-to-not-get-ripped-off-in-pinball-vids-guide