ERP Application Development Project

I am considering several options for Stick Figure's first major project. During my wandering thoughts, I keep coming back to an Enterprise Resource Planning (ERP) system. Of course, this is a pretty ambitious endevor and I wonder if I should start with something much smaller before I jump into something this massive. Here is a mind map that helped me to break down some of the requirements for an ERP system.

Enterprise Resource Planning

I believe that the best way for me to accomplish this effort would be to start an open source project and dual license the product as commercial or open source. I will continue to post the design documents here and I will be using Subversion to host the source code repository.