My concern with the fact that you are seeing this as still a learning exercise is a possible security issue. If you accidentally leave a security hole of some sort, it would leave the investor(s) possibly without recourse. Are you planning on requesting or performing a thorough security audit?
It might be possible for you to program a mechanism for crowd funding the bank roll by allowing anyone to invest.
I could be able to do that part. This might definitely a big project, but I like the idea of coding the basic parts of the site with a more senior developer developing the real sensitive parts of the website. But I do like your idea of a crowd funding mechanism being implemented into the site. But as you pointed I may leave a security loophole without oversight.