Ask HN: What can I build that would pay a dollar for?

I want to build something of value within one month that a lot of people would want and will pay a dollar a month for. I am open to ideas where usually the market charges $10 or more. I am experimenting on a model that needs zero employees, zero evil, no hockey-stick growth ambitions, and yet delivers a great lifestyle by doing what people want and charging 10x lower.

What is your no-brainer idea?

PS: I am a 2-time entrepreneur with 1 small exit and a reasonably successful product startup.