Mock-up designs for new Mobile APP

SourceCloud requires a designer who can create striking creative designs for a new mobile app that we are building.
initially what we would require would be 4 screens designs along with components within those screens.
we can provide wireframes brand guidelines and reference sites to the preferred designer
once these have been approved by the Client we would then need the Full HTML/CSS created in accordance with the initial designs.
There will be some iteration between designs.

This project is for the initial mockups and not the full HTML/CSS
please can you give me a fixed price for the mock-ups and then a price for creating the full designs.
but this work is purely for the Mock-ups the full price is for reference.