Not used one myself, but these £150 ones get a few good mentions on ITRDC2.
3 year warranty too..
http://www.ignitioncarparts.co.uk/PartLists.aspx?PerformSearch=MultiVID&SearchValue='11059','11059'
3 year warranty too..
http://www.ignitioncarparts.co.uk/PartLists.aspx?PerformSearch=MultiVID&SearchValue='11059','11059'