Many years ago, I worked for a place that had been buying demographic, contact and mortgage details of ~10,000 S. Californians, per week, who had recent mortgages. I wasn't involved, but was curious and asked about it. They were paying 10 cents per name, and you literally just had to have a credit card / way to get the broker the money. The data was sourced from Experian.

So, not only easy, but also cheap.