Bit of a bummer indeed, but I don't think you're helping much by quoting £768 for a new headlight!

Why not just consider how much you'd get a good used, genuine one from bmw dismantler for?

I had a quick look on ebay and even an adaptive, xenon one is £349. Surely you'll get one for that or less depending on what type of headlight it is.

If someone came to me and said your bin has broken my headlight and I want £768 for a new one I'd just think they were trying it on.

I think you've worked yourself up over it, I understand it's gutting and all that but maybe a different approach might help.