I like the premise of his site to preserve Playstation history, Playstation Museum is a pretty decent domain name with the potential to be a lot more of a museum than it is now. I guess if you like the idea and think you can do something with it it's probably worth more than face value. If I was loaded with cash I would probably have a go at carrying on what he's started, unfortunately I'm not.
I don't really see how a value of $10,000 has ever been generated. The YouTube account seems to be the best part of the deal in terms of rights transactions. Except for the list of US games and many cancelled ones with a planned US release, the website doesn't even offer that much data. PAL and JPN regions are completely neglected, although combined, they present are the vast majority of PlayStation releases worldwide. And you say this is the best and biggest PS1 website on the best, but how is it superior to Playstationcollecting.com? Not trying to ruin your sale, but a high price calls for justification and potential customers will ask themselves the same questions prior to purchase.