I saw this Estes Vashon V-1 cold power rocket engine for sale on eBay recently. I don't ever remember seeing these as a kid but I think I would have been drawn to it. A blackpowder motor is cool but this stuff looks like "real" rocket hardware. I found this 1969 Popular Mechanics article describing the system.
It's very similar to the Cricket sounding rocket that I found on eBay a while back.