Shopping cart with subscription and recurring payment

Hello, We are building a shopping cart for a magazine website and we need an experienced developer to create some additional features. The website will manage multiple magazines with no fixed release date. This is the list of features that we need : - Ability to import data from XML or CSV file with extra fields support - Users should be able to subscribe to one or multiple magazines and manage their subscriptions - When a new number is released and published on the website, users who are subscribed to this magazine should be billed automatically (PayPal or Credit Card) We prefer customizing and existing shopping cart script like Interspire, Magento, Prestashop or Joomla VirtueMart but let us know if you have any other solution. Please don't hesitate to contact us by email if you need further details. Thank you