How much it would cost to fit iPhone 4 screen?

I cracked my screen and I've ordered a new one in of eBay. How much would the shops charge me just to fit as I've already got the new screen just need it fitted?

We charge £30 for this which i think is a fair price. We only charge £44.99 for the screen and fitting so i guess other shops may charge a little more for just the fitting.