NGUI is a UI system. It lets you create labels, show textures on the screen, and script interaction -- pressing on something, clicking, etc.
A store window is something you'd make using the UI system. There are no scripts to help you here, as this is not a UI task. Anything involving using the UI -- from creating a screen XYZ to the store window ABC is up to you to create.
I suggest starting with the scroll view example that comes with NGUI. It's a scrollable list of items with names and gold values.