Hi @Jalisha Oracius,
Great questions!
For houses, I use DataTree which is First American Title's data company and gives me direct access to all the assessor information about the property, who owns it, mortgage details (if any), & much more. It's public information and legal to mail someone.
How do I know they are motivated? I mail them ALL a real specific cash offer and wait for them to contact me. Typically every 3,000 offers mailed will yield me 1 house. (I am being conservative & there is a bit of research that goes into my offers.)
So that costs me about $1,950 for data/mail total to make $20+k profit on a house flip. (I won't buy if the spread is not good & being conservative again.)
I buy the house outright for cash (not an assignment) and mark them up a little and re-sell fast to a flipper.
*The main point of this whole process* is that I can do this all in 4 hours on a Sunday afternoon and sit back and wait for the motivated sellers to contact me.