One of the best was the Space Patrol Cosmic Smoke Gun, which I wrote about here. It's a bona fide classic; Leslie Singer, author of Zap!, the first book about ray guns, has publicly declared it his favorite gun. I know it's definitely high on my personal list, too.
Well guess what? While watching some old Space Patrol episodes on You Tube recently, I stumbled on an ad for this very gun! Yep, there it was, in stunning black and white, available for nothing more than a box top from some Rice Chex and "twenty-five cents in coin." Hot damn, that's the kind of deal you just can't pass up.
By the way, this is the second part of a three part serial. Since Space Patrol is awesome, I suggest going back and watching the first episode.