It's a legit concern for people new to the hobby. People are conditioned these days to not risk having large amounts of cash. There are stereotypes about people/deals that require cash only. People hear of victims of being lured into places and being robbed, etc.
But what never makes the news is when a seller gets scammed, cards disputed, PayPal fights, fees, etc. so someone new to the hobby, it seems 'off' that people require cash for deals that are so large. Heck, a car dealer will just let you take a car with just a copy of your license... What's the big deal?
So yeah, it is a learning curve for people new to the hobby.
Most of the guidance has already been noted
- make sure someone knows where you are and when you should be back (I call home when I go in for the deal and when it's done)
- take a friend... The more gnarly the better 
- I prefer to not carry the cash on me - I keep it locked up in the car and retrieve it when the deal is agreed to
- and from the other thread... I recommend writing a simple bill of sale which you both sign stating the amount, and that it's sold 'as is' and no warranty
- also, once you paid it's yours... That means you are liable for any damage done to it.. Loading, etc. so if you are going to rely on the seller to move it... Make your choice wisely on when to move vs pay. Some will move it before paying, some will not.
