I have recently started a project in yeast infection niche.
I'm getting 25-30 "warm" optins daily at less than $0.50 each. I could easily scale it to 150-200 daily, but I have problems converting them. The product I'm promoting goes for only $40 and since the people opted in are quite prequalified I would expect the conversion rate to reach 5-6% if properly optimized.
This project has potential of making a few hundred $ daily which I am willing to share with somebody who wants to put some work into testing and writing email copies.