I even go to the extreme of if something I was selling at a bargain price if $100
and they send the $40 offer I say hows $130, then I change the price to $130 in the add and leave it like that, lol, ?
And then when they say ok I'll pay $100 I say too late it's $130 now , hahaha?
Having said all this I always put good prices on anything I sell.
and if something I want to buy is a good price I never question it or lowball the seller! I just buy it.
if I want to buy something and I think it's too dear I don't even bother going to have a look.