Yeah - aint cheap though! Note company is in France so prices in Euros but you do get VAT exemption for non EU international at checkout which reduces the sting.
€ 259,00 Incl. VAT Without the filters €215.83 excluding 20% VAT
€ 459,00 Incl. VAT With the filters 
€382,50 excluding 20% VAT
Kit to replace the original air box with 3x K&N cone filters on Rocket III (all versions).
Details and applications below.
Availability: In stock
Article number:
MSG001 (A)
K&N Intake Kit for Triumph Rocket III Roadster