Airtran is running a good deal, in late september the rate was $168 round trip. If you book Usair, try clicking on finding a flight by way of "price" rather than schedule and you might get a better deal. The price was starting at $150 and with taxes and fees it came out to 162.50.
I was going to book the 162.00 flight one evening but my kids wanted the computer so I thought I would book the next day, by then the 10:30 flight was no longer listed, only a 12:30 flight and I did not want to leave that late. Booking the 10:30 flight was now going to cost $216.00
I went on travelocity and United had the best price for the times I wanted, $172.00, instead of booking through travelocity I went to united.com and the flight on their website was $5 cheaper than through travelocity. The funny part is that since Usair and United are partners I am actually on the Usair flight I had tried to book and I get the Usair frequent flyer miles as well.
You just have to check every day, usually more than once a day, and you may have to take a later or earlier flight to get the price you want. As soon as you see the price you want book it, do not wait.