I have always been intrigued by the Gilbert U-238 Atomic Energy Lab Kit that was only sold for a year, starting in 1951. The kit included a Geiger counter, a Wilson cloud chamber, a spinthariscope, a electroscope, and a comic book in which Dagwood splits the atom. It also came with three sources of radiation and four samples of Uranium ore, also radioactive. It's the most DEVO-esque toy I could imagine.
While it is often identified as one of the world's most dangerous toys–what with the radioactive samples and all–as one commenter to this Chicago Museum of Science and Industry video tour states: Far more dangerous is the progressive dumbing down of scientific toys that has occurred in the past few decades and its impact on childhood curiosity and discovery.
As this video points out, the kit wasn't short-lived because of its dangers ("Dagwood, don't eat the Ru-106!"), but rather, its price tag of $50, which would be around $520 today.