There is an advantage to a well stocked local dealer in that you can go in for something to do something odd - like I am after CG brake arms for a yamaha TLS, would prefer the Ymaha parts or nice ally ones BUT I do not know the numbers, I do know CG ones fit. Can rootle about or he helpful storeman can look. Dave Silver are great if you know what you want / have a VIN / Part Number, they have been unable to help if I ring with the above problem - What is the frame number of the bike sir - no sir that is not a CG that is a CB100 - nope it is a CB 10 frame with CG running gear and engine - they are the same frame, sorry sir I cannot get the part unless you have a `VIN or the part number, etc. Sorry sir I need the VIN for the CG as the arms are diferent or might be, etc etc etc.
However it does seem that the tendency for people to not keep old bikes (over 5 years old) do their own work etc means that dealers do not carry stock - even basic stuff like filters, and order it in for you - so as GC said, why not order it for yourself and get it delivered?
I dislike the idea of ging to the (eg) local book shop, browsing their stock and finding a book you like, going home and ordering it from Amazon - because it is cheaper - you have used the facility value of the bookshop, pay for it. But a dealer who does not carry stock, or who wil not deliver it for free when DS / Crooks / Fowlers etc will does no offer anything of added value.
R