If you have some money, definitely try to buy some sites. And you can do it over time if you need to. One a month, and a year from now you could have 12 nice PR4 or PR5 sites to help pass juice.
I've been creating my own private blog network over the past month and I would suggest hitting the GoDaddy Closeouts if you want to find some cheap sites with good DA/PA. You may have to search through several pages before finding one that meets good criteria, but I can always find one or two within an hour or so of searching. I just plug them into SEOMoz bar and I make sure they haven't been banned in Google or been excessively dropped by the Registrar. It is easier to find high PA/DA blogs in the bargain bins than it is to find high PR and I agree with Matthewmagicman in that who really gives a shyt about PR? PA/DA will help you rank right now.
With that being said...
I do watch the auctions for high PR one's. I use Keyword Domainizer for this, which is kinda a piece of shyt but it does this job quickly. I'm sure there are better softwares out there but I'm not looking for a replacement right now.
I picked up a PR3 that is DMOZ listed today...paid a little more than I wanted to ($89) as there was a flurry of activity in the last five minutes and I let myself get caught up in it. I picked up a PR5 yesterday for $17. You'll have to pay for a year of regsitration and I also to Private Whois so that takes a $17 site to about $37.
Of course it takes about a week for the site to get transferred to you and it is still possible that the previous owner could claim it in that week, in which case, you get your money back. That's actually never happened to me yet.
I've picked up a few PR5's for less than $25 just by spending a little time every day checking out the bargains and auctions.
I use SEO hosting for them so that they are all on at least different Class C's and I will do a redirect (to my home page) for any pages that were linked previously from PR 1 or greater websites.
My SEO Hosting costs $24.95 a month for up to 100 sites (host9). Alternatively, you could rebuild the same link structure for any pages that had High PR backlinks to them. Just use the free version of SEO Spyglass for this.
I have eight sites now and would like to take it to twenty five. I don't sell services or do SEO for anyone right now. At this stage I just use them to help rank my own sites.
Hope this helps. It was kind of a brain dump that may not be in sequential order.