Dear Sir
I'm working on a similar project. Basically at least 60% of the required features (including PDF and Excel export, access management and the general framework) would be ready to use. It's written in CakePHP based on the MVC model. If necessary a front-end site can be added easily. Please let me know if you're interested in this system.
As you can see I don't have many reputation since I just joined this site but I have 7, almost 8 years of experience. I think if you need a complex system like this we could work together.
Please let me know
Sincerely Attila Novak