The best we've ever done (with Southwest internet specials) is $49 each way/non-stop to Orlando.
We signed up to be notified about internet specials and they automatically notify us. You really have to check your e-mail regularly. Usually we get news of a good rate a few months prior to a trip and plan accordingly -- you do have to act quickly though and you won't be able to get those rates by phone -- the reservationists don't have the price info in their computers -- you have to do everything on the computer.
We've never had a problem with the ressies and have always enjoyed flying SWA!
Hope this helps!