You can implement a such a Store with the Soomla plugin for in-app purchases. The layout and design is then completely up to you.
I guess you might want to implement tabs, list available items in a scrollable view, and similar stuff.
QML already provides components for such UI elements, for example:
– ScrollView – provides a scrollable view
– TabView – for showing switchable tabs
– ListView – display a list of items based on a model data and delegate item (how each list item is displayed)
– Grid / GridLayout – helps to layout items within a grid of multiple rows and columns