Based on your restrictions, this doesn't sound like a 'no-brainer' idea whatsoever... I think your best option would be to join a team which is building something of value to a lot of people for one month and charge them 30$ as your salary.
Thanks, Marcelo! One idea I have is to build an email open tracker that does not sell data to third party. Doesn't take time to build and can be priced at a dollar a month. I am looking for tools like these that are not that hard to build if your ambition is not to scale.