Before upgrading your website to PR7 status you need know the importance of rank 7. The uses your website can incur when it is given PR7 are minimum because the PR6 status is very similar to the PR7. When you buy backlinks for your website look at the price difference between the PR6 package and PR7 package and if you find the difference id more then obviously you have to go for purchasing the PR6 backlinks which will save your money for the next backlinks purchase. Apart from the other look up points then you have to follow the same steps to develop your website. You have to chain your posts with in your blog or website and maintain the traffic within your website and then increase the backlinks density to increase the backlinks traffic to the outer web. Select the backlinks according to your domain name.