I was 19 and in my first year of college when I finished my last contract programming job and started working for myself. I launched my first product with a $10 domain name and $17 web template for the site design. It made well over 50K in net profit its first year. I paid my way through college without debt, and run several profitable web apps now.

There are others on HN with similar stories. I recommend checking out the profiles of commentors. A lot of people have their sites in their bios so you can see what they've built.