Pop-up for different mobile phone platforms

We need to create a short advertisement message that will pop up when a user opens a mobile application on iPhone, Android, Windows Phone and BlackBerry. Our budget is 30-50$. See an example in the attachment Here's the specification: xml file is stored here: [login to view URL] Every time a user opens the app the program should check if the pop-up was shown already. If yes, it should compare the show date with the date of the latest content. If the latest content was created later the dialog should be as follows: Title message open the link? Buttons Yes No renew the date of the latest shown message the end