Well don't concentrate on PR itself, you might have the wrong idea of it's importance or relevance in this case. You more should concentrate on a proper keyword and niche research, get quality content with smart headlines and perfect on-page seo in order to hit many different long term keywords, focus on speed of your page as well, after this steps are taken care of, you can think about doing some off-page seo.
For cheap hosting check some virtual private server offers in the BST section and as your site traffic grows consider in getting a CDN. But in my opinion you already trying to care about task you should do as the last step, of course you always go for a blackhat hit and run stratgy, but I feel like you are more aming in building a steady income with your blog.