I am a Ssr. Java Developer with a lot of knowledge about this kind of applications. Have worked on Peugeot/Citroen Argentina two years and i just finished a project for GM. I estimate 30 days in my offer because i don't really know your specifications and i don't want to lie about estimations, however of course if it's a simple project, this time is not real.
I think we should talk about architecture and framework technologies (experience on struts, spring, hibernate, maven, SQL, and more) before start anything.
Thanks for your time.