This is just an idea. It being feasible depends if it goes viral. Use the $20 to run a VM for the 90 days. Host a minimal viable product with different micro services that people will want to use, and charge like 1-5 dollars depending on the microservice. One microservice could be: A person uploads a recording of someone talking, then it gets transcribed and emailed to them as a word document. All must be automated.<p>Hope this give you an idea. cheers.
With only $20 it's more about what service skill you have to offer. And that's not enough to even advertise. So, you would need to go door-to-door offer your services. post of craigslist or facebook etc.