Need an App Developer: iOS, Android, HTML5

We are looking for an experienced mobile Android + iOS + HTML5 developer to copy and enhance our existing app. The app has a search directory basis that sorts listings by distance from user using GPS. It requires social media and camera integration. We need to add a new simple user management console that also has a payment mechanism to charge subscribers to update their listings. The app is free for consumers to use. It should be relatively easy to do as we have the existing app/HTML5. However, we don't have access to the code anymore. Any nationality developer is OK but we require excellent English communication. We will only work with highly rated (4.8+) and experienced developers with a 90+% Completion rate. The URL + additional specifications will be forwarded to the bidders we short-list. We are expecting to pay around $700.