Until you achieve power you are not going to change our system and with out major change none of the hundred or so third parties that have tried have succeeded. Besides my original point that it is easier to influence one of the exiting parties than it is to reinvent the wheel still stands.
Ross Perot was polling at over 40% before he dropped out of the 1992 race and still got over 20% when he reentered. Imagine what an intelligent and charismatic candidate could do if he invested his own money.