I was quoted £5000 for my E63s, but I also had a cheaper quote at ~£3500.
In the end I settled for front end PPF for £1000, then a ceramic coating all over.
I believe it's worth it, just think about the first stone chip you get.
No touching up, only full panel respray and I was told they can't even guarantee a colour match anyway.
I had 2 small stone chips prior to applying the PPF and it covered them, now they aren't visible. Plus the dealership left me a nice scratch on my wing, this is now covered and not visible.