Thanks to Ben for pointing me towards miniorgan.com, a beautiful collection of 70s-80s musical toys, from the Stylophone (1970) to the Music Lok (1992). Highlights include the Muson Synthesiser: "Kind of a Roland TB-303 but much cooler & cheaper", the Realistic Rhythm Box: "This is absolutely the most kicking toy-drum-machine I have ever heard" and the Casio VL-10, which looks suspiciously like my Alesis Ion. It also reminded me that my sister used of have a Mattell Magical Musical Thing which I'm delighted to learn was "A great masterpiece of the golden age of electronic musical toys".