There's a used handgun for sale here in the classifieds. It's a gun that's on the list, and available new in gun shops. The asking price is $50 over MSRP, or about $150 more than the going rate in shops for a new gun. It made me laugh, but I didn't get upset about it.
The ones that crack me up are the overpriced AR ads that say something like, "I have $XXXX into it, so I'm not going to accept anything less".
There's also a way you tell if something is going to be overpriced just by looking at the title. Look for the words "with extras". That's code for 'overpriced".
With that said, I don't begrudge anybody getting whatever they can for their guns. In some cases, I greatly admire their persistence.
ETA: My favorite ad of all time was the guy that was selling his used Thunderwear - and it wasn't even a joke.