I’d look into historic appreciation data for the area before making a decision.

After that, I would encourage you to go to your county recorders office / court to request data yourself.

Out of the 20 letters I've sent, I've had 1 guy get back to me and we were in discussions but weren't able to find a price that worked for the both of us.The issue is that I only have a few houses on my mailing list so far (just places I've walked or driven by that caught my attention), and blindly searching every street and address # to see which houses are actually legal multifamily will take forever and doesn't seem efficient.I know the data is publicly available, I just don't know how to aggregate it in a way that would be efficient and useful for blasting out marketing mailers.Are there any websites that can pull massive lists of all multifamily houses in my area?

With a land trust, the legal ownership remains with the trust, helping to avoid triggering the DOS clause when transferring beneficial interest rather than title.

Some tools myself and others have used: - Skip tracing- Mailers- Data aggregators like PropStream, PropertyShark, etc. 

They would never look at 99% of the 154 units that are listed on Zillow at any given time.I used this exercise to show how opportunities fall through the cracks & most investors make investment decisions based on bad or irrelevant data.

You learn a lot about data and analysis, renovation costs and dealing with tenants which can mitigate some of the fear of investing.

Propstream is great, you can get a lot of data off of there as well as driving for dollars which I believe is also around $99/month. 

The eviction came about after this management company essentially held the house ransom stating they would not vacate the property unless I wire transferred funds to meet their $3,650 demand.

Do you rely on specific data sources, gut instincts, or perhaps a blend of both?