exactly.
i have been studying the math behind the pagerank system for months, and finally i know how to find good backlinks that can increase pr and ranking for 100%
nothing wrong in purchasing links if the intention is to get more traffic for the benefit of the site visitors than tricking spiders to manipulate SERPs and PR but it's not the best way either.. IMO, we should focus on getting quality links the safest(directory submission), quality/related sites and natural way (link bait, decent content)
you were right form that one aira., what important is that get a quality link which have a good/unique content., and it can really help your site., in which you have a relevant content with that site who've been linking.,
Basically what google is trying to say is if you want to pay for links, pay them. If not, work your arse of building your site's pr the proper way by exchanging links to relevant sites.