What is so crazy about it? The way I look at it as it is a form of advertising. They have a PR8 because they earned it. Plus they have a ton of traffic. So the way I see it, it is a win-win for the person buying the link.
First, they get the benefit of increased PR because of the well placed text link. And second they get the added (and more important) benefit of increased referrals from a high traffic site.
As long as the price is affordable it is definitely worth it. And for that you would have to do some ROI analysis to see if the text link results in sales.
For this you could set up the site as a referrer just like your Google Adwords or Yahoo Paid Ads. then you track all traffic from the site, from where they enter the site to where they leave, hopefully converting in the meantine.
So from my point of view this type of link is a good link - not only is it good for the person buying the link, but its also good for the person visiting the site where the link is found.
Just finished listening to the Daily SearchCast and was amazed to hear about, United Press International selling links. It is a global news agency that once rivaled associated press and Reuters(wikipedia entry). You can buy links on different pages of the site and it seems the average page rank is 8!
They even promote it as a "Way to increase search ranking." How crazy is that?!
TJ SINGLETON