Approx. 6 years ago I bought a 1987 Porsche 911 that I bought for $17K...a week later my neighbour saw it and immediately offered be $19K for it so I sold it to him and took my $2000 profit
6 months later the 911 (3.2L air cooled market) went through the roof and that car was sold a year later for $73K....
... that sale still keeps me up at night