Hello Edoardo,
We have created a PDF Magazine Reader for iPhone & iPad as Universal application and we have integrated 3rd Party InApp Purchase System from UrbainAirship.com with Push Notification, which means you can use this application as your own Magazine reader and through the Admin / Control Panel of UrbainAirship you can upload your new issues as and when needed.
If you don't want to use UrbainAirship then we can help you create your own Control Panel in PHP and host that on your server.
Please contact me on skype (rakesh.patel.m) (rakesh @space-o)
Thanks
Rakesh