Each card would have a QR code that has a URL (like Shire Silver does already) and the URL will take people using a regular QR reader to our respective websites. But the URL will have a parameter that indicates the particular model & denomination of the card being scanned.
http://shiresilver.com/msrp?product=SS1agg <= indicates a one gram Shire Silver card
http://shiresilver.com/msrp?product=SS0.05aug <= indicates a twentieth gram Shire Silver gold card
http://whatisthiscoinworth.info/card_value?DCdime <= indicates a Dime Card dime card
http://whatisthiscoinworth.info/card_value?DC0.1xag <= indicates a Dime Card tenth ounce silver round card
http://silvercirclemovie.com/price_list?SC1xag <= indicates a Silver Circle one ounce round
Websites can ignore the URL parameter (like Shire Silver does right now) or they can have their site return a page that only has the value for that specific denomination (I might change Shire Silver to do that). But the app can ignore the main URL and only use the parameter, then display the value.
When making a purchase, a user can have a total in the app. Each card scanned can reduce that total, making it unnecessary to actually count the money - the app does it for you!