Any music shop should sell it. Sinamex where you probably bought your Keystation from (unless it is second hand) will have it. Swee Lee has it. City Music has it. Yamaha has it. Just make sure the polarity is correct. Most pedals at default polarity should be the same. The the past, Korg's polarity is reversed (I'm not sure if this is still true), but then changing polarity is simple (either from the pedal itself or from your keyboard).