I'm here to help. I'm offering my design skills at no cost, all I ask for is one line of credit in the app's About page.
This is my first design. It's a complete GUI for Instapaper. It's very clean, modern, and most certainly Metro. It's extremely simplistic, but still has everything you could want from an Instapaper app. This app rivals even the official Android and iOS Instapaper apps. The design is based around the Bing News app and the People app. If you're interested in developing this app, I feel you could charge at least $3 in the Store, and make a good profit, which I would want no part of.
Below are some images. I have PSDs of every interface from the log in to creating a new folder. If you're seriously interested in developing this app, either send me a message or post below.