Is there a way to restrict a group of users on one site to only see Products assigned to a particular category

 You would create a site group for each location and one for "Super Users." You can set which groups have access to each product in Sites > [Site Name] > Products > Site Groups tab. Please also remember that you can set the pricing based on the user group as well. This would be done in the Pricing tab of the product. If a user does not have access to any products within a category, then that category will not display for the user.
 
Please refer to the article that gives you information on Assigning Products to Site Groups