Buying text link or renting text link used to be a very effective to boost your PageRank. I have rented text link previously. And I can tell you that a high PageRank text link can really do magic to your web page ranking. However, Google is trying to make sure you pay a high price for getting into their top ranking with this method.
Google has been implementing several measures to prevent people to manipulate their search results by buying text links. I cannot tell exactly what they have done but I can see certain pages search ranking and PageRank dropped drastically over past months.
If you are going to rent or buy a text link, make sure the backlink is from a page with content relevant to your destination page. And do not waste money on Pagerank 5 and less. Go for at least PR7. Yes, I know it costs a lot more.
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