Go through your results for flights to Islip in USA with Netflights. Although American Airlines usually has the best prices, it's best to double check what's available for your travel dates.
If you don’t have set dates for when you want to fly to Islip, try searching by month – that way, you can compare airfares throughout the year.
Look out for flights with American Airlines, as they often have good deals. Or broaden your search by looking at other airports in USA.
For even more options, check what other airports you could fly to Islip from. You might be able to make a saving by going from a different airport or city.