How much would this repair costWatch
i would as a shunt like that can bend other parts of the chassis that you cannot see. A decent body shop will be able to check it out and fix it. Don't worry about the cost if the other party is paying.
if not, it might be cheaper to get tow scrap (same colour) doors from a scrap yard but get someone to check the rest of it
car body work is pretty costly and it is possible that the repair is more expensive than the worth
edit- just seen that the cills are damaged
1k would be my estimate.
Then again, it may not be that much if the dent isn't too deep - not easy to tell from photo's!