The theme 'crowd funding' is not unique or have issues that have never been solved. It is not rocket science.
Do not do it from scratch.
Millions of websites a re built on high-level tools, like joomla.
http://www.joomla.org/
Same is true of WordPress.
So now you tell the OP to use a premade CMS which is not the most appropriate platform for their application and introduce a load of confusion...
CMSs have modules for lots of things but crowdfunding is an extremely custom application, there is no real benefit to building this on top of an existing CMS other than using a tool for a purpose other than it was intended. A crowdfunding site is not a normal website with pages of information, it is a completely custom web application. Looking around online I can't find a single decent crowdfunding module for CMSs. You would end up with the majority of your site sitting in a module and a fraction of the CMS actually being used.
I build a lot of sites - The ones that have pages of information with maybe a few interactive elements such as those for small businesses are built using CMSs but a lot of them are completely custom web applications, building this on a CMS is not the right approach. Look at all the other popular crowdfunding sites, they are not built on top of off-the-shelf CMSs.
Geek - Look into web development frameworks like Django or Ruby on Rails - They are designed to let you build web applications rapidly and do a lot of stuff for the developer, yet they do not force them to have to develop plugins for some sort of premade CMS. This is how modern web
applications are built.