Each dealership is independently owned and therefore dictate their own prices on parts and vehicles. The MSRP is only what Ford Corporate says to sell a car for and that's why that price is negotiable. The same goes with parts.
If you've already purchased something go back to them and let them now that if they want your continued business to refund the difference and price match all future purchases.
The difference in prices encourages competitiveness and is what makes America great. *EDIT: (AND Canada!)
<>< Gal. 6:14
April 2013 HOTM
2013 Ford Fun Weekend: Show Class Winner