For me, purchased lists of private (seller-financed) note holders is the way to go. Doing your own courthouse research is extremely laborious and time-consuming. My lead sources regularly compile customized lists of private note holders broken down by state, property type, LTV etc so that there are no junk notes in the list. That way, I know I'm mailing to a bona fide note holder. My supplier also accounts for the 15% of people who move every year so that out-of-date addresses are, in large part, eliminated.
From there, all that I need to do is direct mail the note holders. Usually I do at least 1,000 mailings at a time, sometimes 3,000 per month. I keep my mailing cost down by using post cards. And, since I'm mailing only to known note sellers (what I like to call "high grade ore"), every name on the list is a potential (good) deal.
At any given time, somewhere around 2% of note holders are MOTIVATED to sell NOW, which equates to 20 out of 1,000 so that's 20 (real potential) closed note deals per 1,000 leads at somewhere around 20- cents per lead so if you do the math, that's about $200 spent per 1,000 leads + mailing costs and I find it's really well worth it. Also, I follow up every month or two with subsequent mailings, as today's non-motivated note holders become motivated sellers over the ensuing months. Also, when I market them, I build credibility and can turn over quite a few deals through followups.
If you want my suggestions re some note holder lists, PM me.