Mobile App Security Penetration Test

I need a seasoned penetration tester to probe the security of my production-ready mobile app on both Android and iOS. The first priority is the app itself; backend and API endpoints can follow only if weaknesses in the binaries point that way... (Budget: €250 - €750 EUR, Jobs: Android, API Testing, iOS, Mobile App Development, Penetration Testing, Security Auditing, Testing / QA, Usability Testing)