I got the silver....

[Rock]

Unlike Keith, I haven't actually GOT the silver yet.
I occasionally buy some cheap jewellery for my wife or daughter (neither of whom is into jewellery in any serious way other than as clothing accessories)
My wife bought a dress recently that I thought needed some silver - a necklace or pendant or somesuch - to set it off.
This got me thinking about silver jewellery - not the expensive custom designs but the sort of item that you might pay one or two hundred dollars for.
I surfed a few jewellers and other specialty sites and noticed the considerable variation in prices for silver jewellery that is all described as "Sterling" or "925".
I have done the Wiki search so I understand the basics about silver.
Why is there such a big variation between the Jewellers and the specialty silver outlets.
Is it just about 'margin' and 'overhead' for the Jewellery chains or is there another reason why the specialty shops seem to be able to sell a apparantly similar item (all marked 925) for half the price of the jewellers.
Cheers.