BUT... people already do this stuff for free. Create free Chrome Extensions to make some tweak on a website. Spend hours crafting a script for an answer on Stack Overflow, only to get fake internet points.
I asked the questions above on SuperUser, a website that theoretically does exactly what I'm asking. Someone will probably eventually post a solution, someday. It just takes too long. The site doesn't get enough traffic because no one is getting paid to do the work.
Then I realized I could do the same thing and get paid. It's just a matter of shifting the context. You've no doubt seen any number of sites where people post sample code to help someone, but disappear if it doesn't work, or there's a minor detail left off, etc.
The only change I made is that by paying me, I guarantee you it will work and I'll be around for future changes, extension, etc. A surprising number of people are willing to pay for the assurance over just getting free help.
I do something similar: I write very small programs for embedded systems: simple timers, sequencers, alarms, etc. for around $100. In some cases, we're talking 15 minutes of work, tops.
If I could charge just $30 and instead sell it to multiple people, I would, but the odds of that happening are so slim, I have to have a $100 minimum. The problem is that even for well-defined problems, what people need tends to be so different that the best you can do is have a common framework for similar problems. The code itself is rarely even close to identical