After studying this pretty closely for a couple years, I've come to the conclusion that list building is useless if you're not training people to pick up their wallets and start buying.
The most profitable lists I've had to this day haven't been big or even moderately large. They have been tiny. We're talking 500-1000 people.
But who cares if my list is only 400 people if I can make 700 dollars on a single broadcast?
Personally, I am done with the free opt in bullcrap. Why should I train a subscriber to get on my list for free?
My products aren't free. My services aren't free. My time isn't free.
I feel like if you can even sell a 5 dollar product or a 30 day trial with a credit card on file, that's 10 times better than having someone opt in for free and get some stupid ebook.
So cut it out already. It's not making you money.