Nice idea but you have some competition. Won't mention sites on here, played with a identical solution a few weeks ago. Also found somewhere that is doing a WP app for a one off charge of $17, you download source code, edit it, compile it and submit it to the app store.
I had the exact same idea a year ago. Looked for competitors and found one very good looking that provided this service for free, with a great website. That's why I didn't develop it. I hope there's enough demand so that op has success, though.
Dave