The VL-Tone app contain the factory presets and rhythm patterns in all their distorted and noisy glory, carefully sampled from an original Casio VL-1. Never have so few bits been sampled by so many for so little.
Casio's strange VL-1 instrument sold 1,000,000 units between 1979 and 1984. Trio, the German band, used it to record their huge hit "DaDaDa", and bands like Human League, Devo, The Cars followed suit. And 30 years later it is still backing tracks by Moby and Fergie.
Note that as this is a sample player, you can't edit your own sounds.
Keyboard Synths for under $500