In my opinion, the most useful function of PR is diversifying your link building portfolio. Only in very few niches, it is the traffic source. With that said, you don't need to rank high with PR.
A quick search in Fiverr and you will find a gig that will create 1 PR for you and a gig to submit it to 60 free PR sites. That will do just fine with your link building campaign.
If you want to spend money, SbWire is one of the place to spend.
Hope that helps.
"We Will Become What We Think About"