When I list stuff I list it for what I consider to be a fair price. Isn't this what most people do?
This is on fb. The reasonable people discuss it on the page. The annoying people will send you a pm asking for you to do a 'deal'
Example, I was selling some baby stuff - 20 baby grows, 20 vests, brand new snow suit with tags, hats, cardigans. Most of it I never put on my baby because she was too big. The pictures show it looks new. And it was all from Boden, white company, Next and Jojo Maman Bebe - I was asking £25 for all and this woman messaged me expecting to pay £15!
Then I had listed some things for £6 each and this woman wanted me to send her one item for £6 including postage. Which after postage would have left me with £1.80 recouped for an item I paid £12 for which is still in EUC.
Don't get me wrong, not everyone is like this but some people just want you to give them stuff for free because they haven't got much money as if they're the only ones!