All search results can be sorted by price, but if you find that the rates you are quoted on a particular search are too high, check flights on different days—sometimes there may be special weekend fares or minimum-stay conditions that can yield a lower fare.
You may also be able to find better fares or more desirable schedules for your journey if you are open to the possibility of departing from one airport and returning to another airport in the same area. This option is only available in cities such as London that have more than one international airport.