AgedVS Pr'd Domains

Looking to start my own blog network soon and I am a little confused about what type of domains to get. It seems that high pr domains are the most common way to go but they are expensive and often times lose links over time. Most of the also suffer a dropped domain blackmark and it is hard to tell if the PR will stay the same the next update. I’m thinking that an aged domain with a good backlink profile would be good as well. I would appreciate input from people who have created blog networks on this subject.