You should aware of that buying and selling links is violation of Google's guidelines.

Correction - Buying and selling links for the purpose of increasing your PR is a violation of Google's guidelines.

You should buy links on pages when the subject is relevant, the audience is your site's target audience, and the link is prominent enough on the page to generate enough traffic to your site that it provides a decent return on your investment. If the link just happens to be a static link (i.e. not through an ad server / redirect URL) then all the better, it's possible you MIGHT get SEO benefit from it or you might not. But don't buy a link solely counting on it or not. And don't put any weight into whether or not the link is nofollowed when deciding whether or not it's a good investment.

its not a good idea to buy links for you to have a higher PR..

Well, What can I say? Many webmasters buy links to get good rankings, of course they take all the necessary precautions to make it look link normal.

But like some of them above said it is against Google TOS to buy links to artificially inflate your SERPs.

It's better to have links from the home page of sites.

There is absolutely no need to buy links to your site.

Whatever the purpose if you buy links the paid links should be disclosed through a rel="nofollow" http://googlewebmastercentral.blogsp...d-selling.html

Do not buy link for PR , you can buy link for traffic.

Try to create natural links for the resource rather buying them because Google not recommend paid links.

Your own links are more powerful, predictable and credible than ones deriving from external sources.

Google PageRank technology is a dinosaur that plays an incredibly insignificant role when it comes to gaining rankings in the SERPs, although most of the search engine optimizers you'll encounter in forums such as this don't see it that way, I can't figure out why. I always suggest for people to concentrate on working with your on-site factors (the optimizable web page/site components) and let any Backlink volume develop naturally on its own.