There is no question that getting quality links from authoritative sites will help your site rankings.   In this day and age, it is becoming increasingly difficult, if not impossible to get quality links by a traditional email request. Many SEO companies and link building services engage in “buying links”.   I want to emphatically warn you that buying links is tricky and can actually hurt or destroy your site rankings if not done carefully.   If you are already ranking in the top 10 on some competitive search terms, then I would not recommend using this technique as the reward is small when compared to the risk
Google has expressly stated its disapproval of buying links for the purpose of improving rankings, and Google has punished both the sellers and buyers who blatantly engage in this practice.   Many SEO’s believe that purchasing links is an ongoing strategy is a time bomb waiting to explode, with the worst possible outcome being your site removed from Google’s index.
What Constitute Buying Links? I think that this is a good question, because submitting your site to paid directories such as Yahoo or Business.com or others does not seem to bother Google, even though the intent of the webmaster was to get links more than be found in these directories. There are many cases where money is exchanged, you get a link, but you are not risking Google’s wrath. It appears that if the primary purpose of the payment is not directly for linking but for some other reason, then it is generally considered NOT buying a link. For example:
·         You can legitimately join a trade or professional association where one of the benefits is to get a “do follow” link.
·         The Better Business Bureau is a good (and expensive) link source as clearly its main intent is to provide users valuable information about a business.
·         Your local Chamber of Commerce Site
·         Non- profit organizations that you sponsor, many times non-profit organizations will have a sponsored page that has out bound links to its sponsors.
·         Paid Press Releases- Some press release services allow you to put anchor text links in your content.
There are other safe sources of paid links if done correctly should work for you.   I want to emphasis that “if not done correctly” these methods of paying for links will result in disaster.   Some of these include:
·         Paying a blogger to promote our product or service.
·         Buying a website or domain name that site has a high page rank.
·         Approaching site owners who clearly are not selling links.
In summary: link buying is a common practice and may be required for sites going after very competitive keywords, but clearly there is a risk.