What companies sell hot seller leads?

[John Ma]

I used to see these a year or two ago as banner ads everywhere, all sorts of companies where you can buy an online generated lead by lead for just $50.   Can anyone list any of these companies?  I am looking for projects soon and would like to try buying  50 or so leads and hope to land a project in that pool of leads.

Additionally, has anyone had experience buying a lead whether is for wholesale flip or rehabbing?