Their source must be cheap enough to do stuff like this so it probably rules out DataAxle, Elsevier and Oracle.
They thought I had 'hacked in'. My landlady at the time worked as a secretary at the FBI and misunderstood or did not know the data could be purchased legally through a third party, after I told her what I was doing at a dinner at their house which they invited me to.
I was extremely hung over when they came, I was 25, and did not at all believe they were agents I slammed the door on them (one of them had converse sneakers with their suits though). They slowly convinced me they were in fact legit, I showed them all the paperwork, and shut the site down due to caution. Gave me a good story to tell, ~2005.
Of course. We're not not allowed to know who sold our personal data to shady 3rd parties due to "privacy laws". Hilarious.
We'll have to acquire different set of licenses if we ever have to step into these industries.