Create a downloadable newsletter template

My company distributes refurbished IT hardware in large volumes on a monthly basis using a network of registered re-sellers and small traders. Our sales strategy mainly comprises of weekly emails which are sent to a opt in database using a bulk mail system. Our newsletters are designed using HTML. Please click to view an example of the newsletters. [login to view URL] What we're looking to develop is a template which can be edited by our resellers, in which they can add their company logo, branding and pricing. We have seen a similar system being used by one of the larger new hardware distributors locally. Please see the URL for an example below. [login to view URL]://www.pinnacle.co.za/files/new/templates/2051/TemplateImage-2051.jpg&title=Lexmark-Colour-Printers-Promo-2016. With your expertise please advise the best way forward.