Otamatone Techno White

I've bought it as a funny little instrument, prank of some sort, if I may. Yet it shown itself being pretty educational. You'll learn to perfect vibrato, you'll learn how to play notes without seeing frets or similar markers and it's fun to use since it looks ridiculous.

Switching between voicings is easy, they are different and if you connect the instrument via line out people around you will even hear it. There's not much sense of using it unplugged in case you want to use it as a serious thing.

In general if you know what you're getting you're going to love it, in case you don't know what otamatone is, just go for the cheaper version.