This is a free market economy, naming one's price does not constitute a rip-off. As long as the seller is not misrepresenting the item and/or forcing someone to buy, I don't see the need to warn anybody off. If the item is way overpriced, then nobody will buy it.

It's like seeing a car parked on the street with a For Sale sign - it may indeed be a piece of ridiculously overpriced junk, but would you walk up to it and add your comment to their sign?

The difference between such a car and this forum is that it is very easy to start another thread expressing an opinion here...