In other words, any original ideas on how I can take my site from PR2 to PR5 in addition to just buying links? Thanks.
Make sure that you site has no duplicate content issues. Guest post on sites with authority (easier said then done). You can use sites like myblogguest and bloggerlinkup to find people who want guest posts. If you want to "buy" or "donate" to a college club you can get a EDU link.
Posting to high-pr blogs would be a good way to build up your pagerank, too, but none of those strategies would be free either
My website is a PR5 and I have never bought any links. It all takes time, just make sure you update your site reguarly with fresh content and carry on link building.
Page rank is not something one should worry about because it doesn't really have direct effect on your rankings. However, to achieve a high PR you need lots of high quality links, post unique articles, create lots of pages and build links to your inner pages as well. Setup a link pyramid and build your web 2.0s.
then go on with the legit ways. like manual directory submissions, creating a great quality original content, social bookmarking regularly.