Uh, Bad Proposal
2 months for 20 billion versus almost 2 years under the Mars Direct or NASA reference mission. That's 12 to 2 times the price per month with far less payback for the chief risk of going to and from Mars. Forget it. Let's stick with our plans.
International cooperation is also a bad way to do large projects efficiently. We've proven that with ISS and peacekeeping missions.
Buy what we can get cheap or better quality from the Russians in equipment or services and invite one or two international astronauts along if clearly competitive in abilities to internationalize the project, but keep it firmly under our control.
Regards,
Mark