Once in a while I sell something on Kijiji and I have to say I get all kinds answering my ads sometimes. No matter what you have to offer and how much you are offering it for, majority of the responses go something like this;
- I'll give you half/or they offer half
- what's the lowest you will go
- I'll give you $x (which is usually some ridiculous amount)

No one seems to want to fight for my rights in such cases, but to be honest I really don't care. In fact I usually don't respond to emails such as those or I have fun responding; when can I get the other half?

I was once selling something and locally and someone emailed (did not post this on the site I was selling it on) me informing me that this item was available on sale at so and so and would I sell it for x. I checked out the sale and said sure.

The OP has chosen to fight only for the prospective buyer and not the seller, one could easily take the other side and make a valid argument, in fact that's what a lot have done here. Nothing wrong with that imho.

Most importantly I have never seen a single item posted here where someone was truly getting "gouged". Unless you mean that a lot of items can be purchased at certain times of the year for 20% off from the original manufacturer, then everyone is getting gouged all the time. I also never get the feeling that anyone here is intentionally trying to rip off anyone, ever!

Perhaps this is less a matter of price police rather than of morals police. It's not something I would do because perhaps I just don't have all the facts. I also think people are free to make their own choices both in how they act and how much they want to charge for something that they are selling. If you don't want to buy it there, then buy it where you want.