Well I don't know where you got the idea that this will be lucrative.
the mailing list business is saturated. ...and ultimately, most lists come from a handfull of original sources.
The competition is so stiff that prices are very low....not really much profit margin left.
Now...teaching small to medium business how to capture and cultivate their own customer database...THAT can be a lucrative business. ....With digital variable data technologies becoming the main (being able to produce highly customized mail peices, based on detailed data)...teaching people how to create marketable data, as a company asset is going to be a big niche skill to have.
right now companies who are using cleverly crafted direct mail using variable data are experiencing significantly higher response rates, and doing so, consistently.
It has always been a known fact that personalized mail is superior to basic mail.....now technology is is making it possible for insanely personalized mail.
BUT...it all starts with how well a company collects data about their customer.
smart companies not only keep track of what a customer buys and when...they take the time to communicate with them, learn what they like, etc.