I have helped a lot of non-natives with their application text basically proofreading and editing. I believe with my experience the same is needed for yours. But currently the minimum that can be charged is $250. Which may be too high if the word of your application is low. But just let me know and I will help you on how to change it.
What you would be guaranteed by me(author,proofreader,editor)
1)quality work
2)value for money
3)efficient communication
4)at least 3X of proofreading
5)personal review and feedback
What do you think? kindly click the link below to know my reviews on freelancer.
http://www.freelancer.com/users/feedback_2138566.html?category=48
Also check your PMB for details
Hope to hear from you. Kind regards