Liz, your difference in price within a chain just might be explained this way:

You say one store is "Central" and one is "Local". I'd guess that the "Central" is owned and run by the actual company whose name it bears, but that the "Local" is a franchise operation. The franchisee pays the company for the use of the name, training, advertising, etc., and may be required to buy all or most products from the central company.   

I can see how it would be possible that with the franchise fees the franchise holder would have to charge more. Alternatively, such overhead items as rent for the premises (or depreciation, if the property is owned) may be higher for one store than another.

If there are signficant cost differences (for whatever reason), there MUST be a price difference, or you go out of business.

It might be interesting for you to ask if the Local store is a franchisee of the Central.

Dave Oesterreich