Just rang local dealer to enquire about replacement JCW Soundkit filters, having put nearly 20,000 miles on mine in last 14 months;
Main filter element - £59.95, no stock in the UK.
Secondary filter element - £ no price available, no history of stock, no idea when it could be available.
Going to try another, bigger dealer & one that I bought it from, but I foresee aftermarket filters in the future