Nick mentioned to use caution on posted ads, and I am very careful, but I got caught one time by a very convincing person with the URR I was looking for.  I posted him on the QTH scammer list.  Alway be sure to check there when someone seems eager to offer you something.  I did find my URR's here on milsurp and was very happy with the deal.  Plus, never take down an ad for something you are selling until you have the money in your hand, and don't edit the ad and say 'sold', or 'sold pending funds', just take it down when you have the money.  There are A LOT of people that will answer your ad saying they want it, but when you ask them how they would like to pay, they are never heard from again.  Also, be really accurate on descriptions.  I got burned by a guy who bought a 4BTV I had, and I clearly put in the ad that it had been up for 6 months, which I would think for the normal person would imply it is weathered a bit.   The buyer wanted  his money back because he said it was not bright and shiny,  I kid you not.  He sent it back after I sent him the shipping money and what he paid for it.  I advertised it again, and put in the words, "this antenna is not bright and shiny."  The guy that bought it was happy as a clam, and put it up immediately.

Charlie W4MEC in NC