Want to know something sketchy? Some travel sites track your searches with browser cookies and use it against you. If you routinely look for the same route and dates, these sites will start to increase the prices in order to scare you into booking. To combat this, search for flights in “incognito” or “private browsing” mode to see the lowest prices.
Not sure how? In Google Chrome or Safari, hit command/control + shift + “N.” For Firefox or Internet Explorer, hit command/control + shift + “P.” A new incognito search window should open automatically. If you want to start with a clean slate for each flight search, then do this every time: Close all incognito windows, open a new one, and then search.