I made accounting program in basic (can not remember the flavor) for local grocery store while I was in high school (can not remember the year). I got some fruit for it. The best bananas and oranges ever. :)
I wrote a login system and download script for a friend for (I believe) $200. Guess I was about 14 at the time. Ah the days where PHP was my hammer and everything looked like a nail :P
At age 13 I had a BBC Model B with a Watford Electronics EEPROM board. I wrote some assembler for custom *FX extensions to match those the BBC Master had for burning ROM images into its built in EEPROM. I was paid £10 by a magazine for the rights to publish the source. I think that bought half a box of 5.25" disks at the time.
I made in to the software business at rather late age compared to many in the business. I was 20 and as a freshman at a university when sold some PHP code to a fellow. It was rather simple data manipulation with couple of db tables but it took me something like fifty hours to do. I could probably code that same thing with Django in ten hours.
Here's a challenge for you: reimplement your first sold piece of code.
When I was in college, I sold a AJAX sudoku for $40. The buyer came to me, and I hadn't even considered selling it before.
Later, I sold some PHP code for $250, and then a web site for $3,000. See the pattern? Next time, I'm hoping to get $50,000. ;-)
I wrote an off-line catalogue system with a redistributable previewer with a 80286, MSDOS compatible graphical interface. It was done in Delphi, turbo pascal and 80286 assembler.
Sold it for around 500€ if I remember correctly.
The first piece of software I sold after starting up by business... A VB.NET demo application to go on a kiosk which demonstrated how a hotel could have a way of allowing customers to select and pay for which channels they wanted in their room. £200.
I wrote a student schedule planning system for my high school in Visual Basic and sold it to them for $200 NZD - which was just enough for an academic copy of Visual Basic, which I'd previously been using a pirated version of.
I wrote a data-entry application for my Mom's workplace when I was 15 or 16 - they had a paper survey going around and needed to tabulate the answers. I can't remember if it was in C or Turbo Pascal (I'd love to see a copy of the code so many years later!), but I remember that the questions were laid out to resemble the paper form and I paid some attention to being able to fill them in quickly. They ended up giving me a cheque for $150 or so, but we hadn't really discussed payment up front, it was more of a way to keep busy during computer class.
By some coincidence, I've got to spend a few hours today turning around some survey code for a client...
Looking only on sold code, meaning freelance work, I think it was 2 years ago, when I was 24.
It was for solving a bug that turned out to be related with how .Net 1.1 released COM interfaces. The pay was, I think, about 350$ with that time's exchange rate, for about 4 hours of work. Sometimes you just get lucky.
Asaf.