Perot was a serious challenger because he could put in a few $100 million. This remains true for any serious third party, they need a way to raise at least $250 million to run a credible campaign.
Bill Gates could do it.
Otherwise all a third party candiate can do is become a spoiler (ie Nader in FL in 2000).
None of the candiates listed in this poll will get more than 1% hence they can aspire to be spoilers only.
I agree with you to an extent. It is doubtful that anyone without an over-whelming cash flow can wage a serious campaign for president. But in this day and age, people are getting more and more fed up with the two party dominance. A lot of people want change...
http://www.rasmussenreports.com/2006/April%20Dailies/Election%202008.htm(there was one that showed a similar result, but with Universal HEalth Care being the twist - Rasmussen messed the link up)
I think a third party threat could be on the horizon if the major parties don't do something special here soon.