All project marketplaces focus on Freelancers. But most of their TOP Developers are companies. But client still treat them like freelancers. I am not saying there is anything wrong with freelancers but truth is quality and real business is done by professional at organizations only. You may hire freelancers for small tasks like on fiverr.com but you cannot do the same for large / complex projects.
If you post such project on these standard freelancer portals, you get good proposals but you will also get unqualified bids which may end up wasting time in interview process.