That sounds a good price is that the twin or single fan setup.
a mate of mine with a j reg rangy phoned one of these adds in a landy mag and got quoted near on 300 quid. thay say about a 8% fuel saveing with this mod. plus the heater should warm up a bit quicker. i know every time i take mine in for a mot i have to rev it for about 5 mins to get it up to temp so the garage can take a reading.