T F G in newcastle sell them, about £190 ish i think,but don,t quote me on that.
They can also fit it for you, once again not sure of price charged but they say it,s a bas*ard to fit the cold air feed to a 172, but once fitted they said it transformed the car, the lad that had it fitted said he nearly sh*t himself the first time he drove it.
They also sell really good cheap ICE and they can get you just about anything you need for your car at really cheap prices.
P.S they are also known as BASS-MECHANIX if that helps.