Cheap flights by waiting at the airport?

I have two sons who are about to WWOOF in New Zealand & are trying to find the best deals on airfare from Texas (Dallas) to CA, then Air New Zealand on. What are the best suggestions you guys have that could save them some money? Any special websites or should they go direct to the airline websites? Help!!! :)

Just a bit of numbers: Airlines manage to fill about 70-85% of their seats on yearly avaerage (which is called the "load factor") but some routes might have a load factor close to 90%.

TexasChick, you will get the best response by posting your question as a new thread. When you make your new post, could you clarify something? Are they just looking to get from Texas to California because they have already bought the ANZ tickets (in which case, what Calif city?) or are they looking to price the whole trip?

Well there was some truth to the story, but industries all change, especially as budget airlines force lower airfares. When airlines could charge a lot more for a seat, any extra last minute bookings were a bonus. With cheaper airfares they need to fill the planes to make a profit.

Yes. I just did it. Fall 2011; I jumped ship in the Windward Islands (drunk doctors on a sailboat, and I got off quick) got a flight to Puerto Rico and wanted to get back to NYC. Walked up and down airport lobby for two hours; $350, $320, etc. Getting late , most flights had left, was about to give up and find a hotel; with 10 minutes left this airline had a few seats open, and the ticket agent sold me one for $120.