If you are interested in getting into website buying and selling these articles are must reads -
How To Buy A Website And Flip It For Profit
How To Sell A Website - How Much Is Your Website Worth?
It's probably worth reading this article about niche content websites as well because if you are looking to purchase websites often the sites operating in a niche will be the ones to look for.
How To Make Money Online Using Niche Content Websites
You can try this podcast as well which includes some discussion of buying and selling websites -
Internet Business Conversation With Michael Pollock