I built my first paid product, "Break 90 in 90 Days", which is a 20+ hour video course for golfers who want to break 90 and learn the game of golf.
Sold the beta launch for $99/course, and got 6 purchases off of an email list of about 1,500 (that I had not emailed in over a year at this point).
This was a huge milestone because it was the first paid instructional product that I had ever sold.