Create the specific header and footer elements in the site's master page.
Create separate user controls for the specific header and footer, and add each of the user controls to the site's master page.
Create a sales subdirectory. Add a master.aspx page that contains the header and footer to the subdirectory, and then store all the sales pages in the subdirectory.
Create a sales.master page that contains the header and footer and inherits from your site's master page, and then use the master page in each sales page.