Back-end Android developer needed for application

Currently, there are 3 of us working on a unique app, which we believe is open to a wide audience and there is no competition on the Google Play store currently. One of us is a graphic designer and has already designed the graphics for the app. Another freelancer has begun writing the actual android app, and I am the project co-ordinator and will focus on the business side of the app. We plan on splitting the ownership of the app 25% per person, assuming there are four of us in total working on it. A contract has been made to ensure all profit generated are split equally between us. We now just need a back-end developer to create a search service for the app, which I will provide in more detail to the bidders. The search service will need to use certain API's from websites and gather information which is then returned to the app and displayed to the user. If interested you will be paid 25% of any profits generated on the app from Google Play. Initially we plan to charge the minimum of £0.99 per download, however we expect a large amount of downloads from this app. You do the maths :).