Have you ever seen a film in a catalogue or dealer's list; you fancied it, but didn't grab it, and later when you get to see it on TV or online, you realise you did right not to buy it. This happened twice to me. The first time was in the 70s when Powell Films listed 'The Reign of Terror', a story of the French revolution, starring Robert Cummings and Richard Basehart. I always fancied this but there was always something more important to buy, then Powell ceased trading, and I regreted I hadn't bought it. The film came up on TV last year, and I was glad I hadn't bought it.
The second time was when I got into 16mm, there were a number of Errol Flynn's on offer. One was 'Crossed Swords', made by Flynn's own company in 1953. I chose to buy 4 Flynn titles that were in better condition. For years I regretted not buying this, then someone put up the film online. It was so bad I couldn't watch more than 15 minutes of it, Another narrow escape.