Hello Nato1, I have also wondered that, but with all honesty it's very much doubtful.
If this guy paid $500 per PR6 domain then it would not make sense to only charge $20 per post.
If there are 10 posts on the homepage of each blog then he would only have made $200 which would not even cover the cost of the domain, and that is without the cost of his content writer.
What matters to me is how far away my post is going to be from the homepage. A monthly archive woulld be good as long as my link does not go to deep.
I purchased 5 blog posts which I'm sure is going to have some ACTUAL pagerank pointing to them, and for the price of only $70 with the content written for me aswell, then I have got a bargain. Where else can you get a blog post on a PR6 domain for that price?
I purchased mine 3 days ago, looking forward to my report.
I will post my honest detailed review as a sucessful SEO practioner of more than 5 years once all of my links are live.