Yesterday I was making a checklist of things I have to check in case I want to buy a new website. Suggestions for extra's are welcome. Here is the list :
General information publicly available on the Internet : 1. Whois information 2. Links in the search engines (Google, Yahoo and DMOZ) for the specific domain. 3. What's the history of the website (via the Wayback machine on [web.archive.org)...] 4. Alexa ranking 5. PR for the main page
General information submitted by the seller : 1. Financial information 2. Traffic information
Page specific information : 1. Spider the website and see how much pages it has. 2. Check the PR per page
I have bought and sold a few and would add to this list :
Check IP to see what other sites are hosted - also check higher and lower ips in that c-block. Maybe they own more than one site on the same topic and are selling the "black sheep" or they duplicate sites with same content and keep selling them as turnkey sites.
Also, check to see what kind of backlinks. Are they purchased? Are they from the owners own network? If they are from the network - make sure they leave them for a period of time so you can go get your own natural links.
Non-Compete agreements. This is based almost entirely on trust, but don't layout all your cards and show them what you know about their operation. Then check up on them once in a while to see if they are honoring agreement.
If they have advertisers - who gets the prepaid money? Is that transfered with the sale? If not, ask them to lower price accordingly. How long have the advertisers been on the site, turnover rates, etc.