Converting Leads, how to get off market #'s

[Account Closed]

When finding off market properties, does anyone have any recommendations on how to best go about finding phone numbers for houses that are off market?  I have used datafinder up to this point, but it costs a minimum of $100.  I am looking for a consistent way to convert my massive lists of potential leads to phone numbers I can cold call. 

As always I appreciate any and all advise.  Thank you