The way you find them is you talk to everyone, you tell everyone you know you're looking for an old bike parked away in someone's garage, or shoved out in the back yard with a tarp over it. Tell your mailman, mention it to the UPS guy who services your area, talk in your sleep about it - and look at Craig's list at least twice a day. If your community has a local paper advertise in it (wanted, cheap honda with a title), and if not see if there are community bulletin boards you can post on and read from (there's on in our Post Office) Then chase down every lead you get. Oh, and don't forget E-Bay. If you're prepared to drive two or three hundred miles, one-way, it goes a long way's toward scoring a bike.
My own experience makes me a "no title, no deal" kind of person. You decide for yourself on that one but find out what it will take to get a title in your state before you even consider a bike with questionable paper. Other than that keep enough cash immediately available to jump on a deal the moment it appears.