Improve the graphics on a software application story board - open to bidding

I'm working on an application for a non-profit organization that seeks to help people build long-term wealth through savings, tax deferment, and investment. I have a story board concept for a web base application that needs a designer's touch. I tested the concept with users got a very good response. Now I'll need to start building it and need some ideas for the graphical design. Phase 1: I'd like to start with a 2 to 3 concept renderings to pick the best look-and-feel. Once that phase is complete, I'd like to have you render each screen. Can provide an estimate (a range is fine) for Phase 1? Thanks, Ron