You'd pay $10-20/month if something just workedIf you are selling to ‘enterprise’ that business model might work well as a per-seat price.
At retail, into small bespoke niches a business built on $20 problems is unlikely to be sustainable because it is not enough money to reliably reach small markets and it is not enough money to sustain high quality service to a small number of customers…sure 1000 customers would be $20,000/month, but you have to get there first and stay there second.
Getting there is probably more money and calendar pages than you think and staying is going to gobble up more of the $20,000/month than you want through churn and employees.
My advice: find some thing you want to work on or find actual customers who will pay you handsomely to solve their important problems. Good luck.