The new MidiRig pocket sound module is an excellent choice for an accordion MIDI expander.
You can see more information here: http://midirig.com/products/sound-modules/midirig-pocket-expander/
It is super compact and easy to use with a wide variety of sounds. The 10 programmable presets give instant settings right out of the box.
It is also able to power directly the MidiRig accordion MIDI systems.
We are offering this with free UK shipping currently. Just select 'Pick up at Store' during checkout and add your delivery address as a note on the order.