Let's dispel this PageRank myth. One of my client's website, which get's over 3 million unique visitors every day: Alexa Traffic Rank 1,496 Rank in US 384 PageRank 5 My Friends website, get's 40k unique visitors per day: Alexa Traffic Rank: 58,180 Rank in US: 14,286 PageRank: 3 My Partner's website, get's 1.5k unique visitors per day: Alexa Traffic Rank: 364,808 Rank in GB: 91,961 PageRank: 4 My Personal blog, get's 60 visitors per day Alexa Traffic Rank: 6,634,128 Rank in US/GB: none PageRank: 5 So there you have it, small inactive blog with 60 visitors a day has the same PR as a 3,000,000+ visitor a day website that makes over $100k a month in ad revenue. Facts, you have to love them.
Actually this is not a myth but a misunderstanding by many noobs. PR is not directly related to traffic or revenue but many noobs believe it is. A site that has no PR can get more traffic than one that does by simply doing Viral things like Social Marketing(can be very Viral),Press Release(can send short rush of traffic), 1st page of Digg(viral), etc Where as another site can focus only on high PR backlinks(nothing viral, maybe not even niche related so no real traffic) but never really receiving a lot of traffic from it, just PR. A PR1-2-3 site can out rank a PR4-5 site in the Search Engines thus should be getting more traffic. I can also go to Godaddy Auctions and buy a PR5 at auction, that doesn't mean when I post content to that domain that traffic is going to flood in. But to prove a myth/misunderstanding you have to compare apples to apples. The sites you reference above I doubt are targeting the same niche/keywords. But I understand what you mean just wish so many noobs could get this to sink-in.
There's also the elephant in the room... it's PAGE rank, not domain rank, so buying any domain based on the PR of the domain homepage itself, is about as useful as buying it based on how hairy the previous owner was.