You can purchase full or upgrade version for QuarkXPress with best deals available at www.quark.com. Navigate to Buy on the menubar to get access to Quark Store / latest promotions etc.
In case you need more information, contact Quark at http://support.quark.com/contact_us.html
NOTE:
- You will need to have your current active serial number registered in order to be eligible for the upgrade.
- You will only be able to save back one version. As an example, if you have upgraded to QuarkXPress 8 you will only be able to save back to version 7.