Build Microsoft store in-app purchase SDK - repost

We need to build library for windows 8 (windows phone compatible) that will enable third party in-app purchases. This library should provide following functionality [login to view URL] On the Processing Payment screen it should show remote HTML. For this project this HTML should contain 2 buttons - "Accept" and "Reject". In case of Accept button pressed - it should be Payment success event. Please include kakashka in top of your bid, so I can understand that you are read requirements. I'm not realy familiar with Windows 8 yet, so probably requirements needs to be a bit clear. If you have question or suggestions please write PM.