depends, sometimes you can pick up a charger for £100-150 but then it'll need a service. Or perhaps £350-600 for a serviced one.
It may not be dead tho - get the damage looked at if needs be before condemning it. It you have some circlip pliers, side cutting pliers and some allen keys then i could talk you over dismantling it over the phone - after you've got it off the car. Either that or ship it to one of us (or g-werks) to inspect it.