Here you go Scatz. Might be worth giving this bloke a ring at the link.
Got here: http://www.alansmith.co.uk/prices.htm
Then scroll down to the automatic window closing bit. Here it is for quicker reference:
Automatic Window closing *
To auto close two windows from alarm: £99.25
To auto close four windows from alarm: £99.80
Total closure including sunroof (Can only interface with certain models of vehicle - some vehicles are not suited to sunroof auto closure): £135.89
If you click the title, Automatic Window closing , then it will take you here: http://www.alansmith.co.uk/alarmselect/window.html
There isn't much on this page which is the reason I said might be worth ringing him.
On another note, I thought this was very interesting: http://www.alansmith.co.uk/alarmselect/68hi.htm