From 01 January 2018 an operator shall not operate an aircraft in European airspace where carriage of radio is required unless the aircraft radio equipment has the 8,33 kHz channel spacing capability (see Commission Implementing Regulation (EU) No 1079/2012 of 16 November 2012). Further information for aircraft holders can be obtained from Eurocontrol's website 833radio.com. This register is an information resource on 8,33 kHz radio equipment, mandates and funding opportunities for General Aviation operating in the European airspace.
There might be a possible support by the EU for this invest. Please read more here!