not an area of my expertise but I do think folks do well going to the bigger paper source type events and mingle and there could be bulk sellers there..
As Chris said, network as much as possible by attending both national and local real estate events. You should also contact asset managers frequently and more than once. I was taught by Scott Carson so i am a little biased but I found his method of teaching to be the easiest to understand. Dan Zitovsky also has some great content and just released a book discussing his methods. There are a few facebook groups that can help with questions. The best thing about note investing is that people actually help!