You're well under the most significant advance purchase discounts, so prices aren't going to be too cheap. Even WN wants $450+ r/t to go to Islip/Long Island on that date because it's so close.

Unless you're sensitive to the exact time or airline, I'd have to suggest Priceline/Hotwire as your best bet for a discounted ticket. Sometimes as it gets closer to the date the PL/HW prices drop as the airlines are more inclined to do whatever they can to get the seats filled. If the planes are already mostly full, though, you'll not be able to find much of any discounts out there.

There's also the possibility of the last minute packages, like Travelocity's Last Minute Deals and Site59 (they pull from the same resource pool, so there's no reason to check both as they'll give the same options). Dates on those are restricted and are usually just for a few days at a time, but can also get some good deals. I bought one a while back and did a throwaway on the hotel part of the deal because the airfare price was so much better than I could get otherwise.