How many times have you wanted to kick yourself for letting a good deal on a flight pass you by? I have experienced that feeling one too many times. Fortunately, British Airways now has an option to reserve a flight and lock in the price for up to 72 hours (with a small fee, of course). For around $10 you may hold your flight, however your deposit will be forfeited if you choose to not book your itinerary within 72 hours. This option will be available on most but not all flights, due to "complex fluctuating tax complications".
Airlines that offer similar options when booking include but are not limited to: United, South African Airways, and the new American.
Trusted Travel Girl Tip: Some airlines also allow cancellations within 24 hours of purchase (100% money back). These policies are constantly changing so be sure to check the airline's website beforehand for the most up-to-date information. I have personally been successful canceling within 24 hours on both Delta and United.