It's all very incestuous. I suspect that part of what happens is that new companies are comprised of people who have previously worked in the industry, so they have general knowledge of who the available providers are. Without prior experience in the industry, I suspect you're not going to be in business very long.

The other part of getting initial sources is probably calling companies in retail, insurance, etc and pitching them on how much they would make selling customer data to them. If I had to do it, I'd probably get industry reports, sort by annual revenue, start at the top and work my way down as I try to get a hold of the consumer data department at each company.

I've also been approached by these guys when I was part of shutting a company down. They wanted to buy our customer database. I guess when one of these companies shuts down, some new one can buy the database and use that as a seed for new operations.