Just had me sapphy done and it was £30(fully comp),had it not been heated would have been free!!
A lot of glass companies now work the excess in to the price, but it depends who you are with as to what the limit is on the glass.
On my other car which does not have a heated front screen I pay no excess at all, only downside is I have to pay ALL up from then claim back as they will not direct deal, trying to force me to use AUTOGLASS, who would be my last choice round here.
My advice shop around a lot and barter them against each other, but keep a reference number of each, as they will ask who the cheaper quote was from.
tabetha