There are many other options available - the groovebox market is booming right now. Even if you don't consider traditional grooveboxes like the Digitakt suitable for creating an actual "song", options like the Polyend Tracker are available and the modern MPC devices are basically a DAW-in-a-box now, complete with software synths.

The OP-1 is cool as hell, but realistically it's a £500 musical toy marked up to £2,000 simply because hipsters latched onto the design and marketing of it.