How to build a blog network
1. Buy a seo hosting, with lots of ips, different c class, etc.
2. Buy domains + private registration. For every ip you bought at point 1, you can put up to 5 domains on that ip. (some put up to 10). Install wordpress manually on each of them- if hosting has cpanel and fantastico is simple - or buy a plugin/app that does this for you.
3. Find a solution to post a spinned content on all the domains automatically. Some software have this option included among other- the best spinner, amr, etc.. . There are also more pro solutions dedicated to multi posting.
4. Now you have a blog network. Improve its quality by building links to the domains, adding pr/old domains in the network, posting content at a decent rate - do not spam it with 20 posts per day or etc.