I don't know of anything else with the functionality and low price of the KeyStep - Keyboard with velocity and aftertouch, arpeggiator, sequencer, DIN and USB MIDI, CV and gate.
You might be able a to pick up a small controller keyboard fort slightly less (with some bundled software, e.g. Ableton Live Lite for sequencing) , but then without most of the above features, and in most cases the need to have everything connected to a computer to make it work.