I have been trying to utilize different services which provide you links from high PR pages. Recently I bought a package of 24 links from PR3, PR 4, PR 5 and PR 6 pages. The 24 links came down to about $450 in total. In the package PR 3 links were the most but the PR 6 links were the least.
As soon as my order had been fulfilled, I checked every single link location to make sure that the links were DoFollow. I also checked the number of outbound links per page, which, to my surprise turned out to be over 150  links on average.
I have been consistently tracking my results from these new links and I am a little disappointed. Although links from high PR pages sound really good in theory, when you actually try to put them in practice they do not work that well.
The first reason for the lower ROI they provide is simply the higher price that they charge. For the $450 I paid for the 24 links, the average comes down to around $20 per link. Now, because this was a discount package, had you bought these high PR links at their normal price, you would have paid almost double.
The other problem with the companies providing links on high PR pages is that they put so many links on the same page, that the whole process loses its value. Think about it. If a company puts 200 outbound links on a single page, the link juice sent to the target is severely reduced. It boils down to you paying much more than you get out of the deal.
As far as the rankings go, I have seen no improvement. This might be due to the fact that I am already number 8 on Google for competitive keyword phrases, but I had personally thought that 24 links from high PR pages would help me move up a rank or two. This did not happen.
In conclusion, even though buying high PR links can be really beneficial, you have to understand the whole process before spending money. Always ask the SEO company about the number of outbound links on the pages they provide you the links from. It makes a huge difference.
I would instead suggest going for links which are put up on the inner pages of high PR websites. This makes sure that they are much cheaper and more effective from a price point-of-view.