Determine costs of app design

I`m building my first app, but i have no experience in design making, so i want to hire someone else to create it for me. But because i dont want to be scammed, before hiring anyone, i wanted to ask an approximate estimation of design cost, that would consist of following elements:

1. Launch icon
2. 4 notification (status-bar) icons
3. Action Bar
4. 3 activities with backgrounds, several buttons, text views, two one-color images and one custom view animation
5. 3 Dialogs (title, description and buttons)
6. My question is, how much would this design cost (based on list above)?

— modified on Aug 31, 2013, 6:28:56 PM