Bought mine through Heritage in Bristol and dealt with Adrian. Rather than put a % on it I would rather say that yes it may be possible to squeeze out a few pounds somewhere else but if you are local and looking for a good deal then I would recommend them. I wanted a good deal and good advice and that is what I got. An excellent buying experience and feel very confident with the final order which was very important to me. Peace of mind is worth a few £ and an enjoyable purchase to boot which is how it should be with a Cali.
NB: He certainly knows about most of the options because as someone rightly pointed out I chose most of them.