I'm very experienced with setting up PBN's and I'm currently hosting 50 for my money sites. I never paid a dime for them and mostly used Xenu to find them. What I also do is using WHOIS information to contact registrants of soon-to-expire domains. It's a huge struggle with a very low succes rate, but in the end it's all worth it. While I had some small successes in the past (3x PR 2, 2x PR 3 domains) today I hit the jackpot: a genuine PR 5 domain! I wrote to a company who had hosted a charity event in 2012 and was about to drop the domain. Kindly asked them wether they wanted to sell (I only ask this for PR4+ domains) them to me. I was blunt and told them I'm an SEO guy and would partly restore the old site. Also told them in couple of days the domain would be free for any average Joe to register and it might be abused. Today they contacted me and said they'd hand it over for free. Quite estatic right now honestly! The domain has some awesome backlinks from one of the world's most familiar NGO's (the event sponsored them) and numerous other high quality links. So guys: be proactive and always contact the owners of expiring domains. Most of them don't know the value (duh! that's why they let them expire in the first place) and once a fortnight you might get incredibly lucky like me.