When selling domains many domainers struggle with pricing their domains. There is the fear of losing the prospect by asking too much, while at the same time worrying about under pricing the domain.
Of course the best position to be in is that of an unmotivated seller. Where turning down $5000 can be done with confidence. Rick Schwartz has illustrated this technique at the highest level.
There are a lot of things that go into pricing a product, some may be emotional, some psychological and some just based on pure supply and demand.
Kiss Metrics just wrote about 5 psychological studies about pricing.
The article is not about domains specifically but is a good read for anyone looking to price their product. This article should also be helpful for those looking to price their product on their ecommerce website.
One of the things in the article is a video from Dan Ariely who spoke on pricing.