I noticed recently that Text Link Ads has a new service (or new to me) called ArticleLinks for building link popularity and helping with SEO. $600 gets you an article on any topic and a 'guaranteed' 20 links from other sites using relevant text for your keyword.
At the end of the day it is a link building exercise and they set the price at that rate as it is the 'experts' behind it... although their distribution could well be to the same article sites that most people distribute to normally.
Interesting, I might have to look into this although $600+ is quite a bit of money for one article.
I had been considering this approach as offering the service myself, although $600 would be great to be able to charge, I feel it is out of the budget of most smaller webmasters.