After finishing grade 12, I had some time on my hands before college began. At this phase of my life, I was really into AV equipment and gear, and audio production software. To fund buying things from the only Radioshack in Oman, I was always trying to come up with ideas on making some money in the right ways.
So I came up with a audio cassette tape conversion business. For $5 (R.O 2, in local currency), I turned any two sided audio tape into an audio disc. I didn't have any special tools to do this, I just plugged the speaker out on our home music system to my computer's sound card, and then ran audio cleaning tools inside Audacity. I probably put in $20 worth of effort to make $5, but in a country where there is no idea called minimum wage, and where kids don't actually get jobs, this was exciting to me.