And then there are diatonic accordions, which all use a similar layout both for the bass and melody sides (but you can't play in all keys[0] on them, that's the difference between chromatic and diatonic). While they are simpler than chromatic accordions, they are now usually more expensive because fewer people play them.

[0] that is, ~"scales"; usually all buttons will be working

I can't find it now but a while back on R*dd*t /r/synthesizers there was a diatonic Korg Triton that someone had clearly had custom made - possibly from the guts of a diatonic MIDI accordion, not sure.

It looked pretty slick, not the usual homebrewed raggy-edge crap. Someone had clearly spent quite a lot of money on getting *exactly* what they wanted.