My first boat was this little guy, a Mac Dinghy (but not by Mac Boats--this one has tags indicating a J.L. McReynolds Company in Pittsburgh, PA), which I purchased used for $400 this summer. I learned to sail on it in St. Martin Bay (Michigan) on Lake Huron while on vacation. I carried it on top of our car. Now it's looking for a new home so that we can get an O'Day 25.
[edit: forgot to add my age at the time of purchase: 30.]