Connor,
You can buy the individual parts cheaper on fleabay, but it still comes in close to £95 / 100 notes,Although there are currently a set of switches on auction and the bracket is only £13. Or you can buy a kit all included for £100 for the black switch, or cheaper for the grey switch £75, depending on whether yours is a facelift model or not. Try searching for Discovery 2 cruise control kit on fleabay.
I know this as I got a kit last week, just got to get the motor back to fit it.
Cheers
Neil