GTS800
This Garmin traffic system only got EASA ETSO approval a couple of weeks ago so I doubt anyone has had time to complete an EASA design package and get an AFMS approved. If you're on the N reg, you can ahead immediately using Garmin's FAA STC which covers loads of aircraft.
The $13000 cost you mention would be comparable in Europe (excluding VAT). A similar cost will result if you went for the Avidyne TAS600.