Discounts for summer flights usually don't hit until about 3 months beforehand. So wait until May unless something comes up such as a Southwest $99 each way special. Problem with Southwest sales is most of the sale seats are gone very quickly. One way to make the trip is look around to buy a free flight on Southwest. Lots of them on sale on Craigslist and other places. Going rate is usually around $300 and they are fully transferrable so shouldn't have much to worry about. Generally the best way to make a last minute flight because the free flight isn't subject to fare categories or any complications, just has to be any open seat and you can reserve it.
For reference, best order of action is to go to Orbitz, Yahoo and Expedia. See who they say has the cheapest fare. Then go to the airline site they say has the cheapest fare and do the search to see what price they quote you. Then go to Hotwire and see what they quote you, rarely will be cheaper than what you have found. Then go to Priceline and offer about 15% less for a ticket, but beware of all the fees. If you want to control your schedule, skip Priceline and Hotwire and just buy the cheap fare. Rarely can you get a better deal for a flight than on the airline's website these days. All these sites are big into the lowest fare guaranteed thing. They don't technically apply to Hotwire/Priceline, but I have noticed for flights they generally don't let fares go for much of a bargain anymore. Hotels are a different story though, you can get some screaming bargains on Priceline if you know what you are doing.