That's what Consumer Reports' Tod Marks found when he investigated how to cut the cost of flying.
"You see a lot of airfare deals out there that sound great. But hidden fees, fine print and blackout dates can make locking in a great deal as tricky as a soft landing in turbulence," Marks said.
Take for example a recently promoted Travelocity deal on a round-trip flight from Philadelphia to London for $277. Once you book, it actually costs nearly $666.
"Spirit Airlines promotes flights that cost as a little as $9. But to qualify, you have to join its $9 club, which costs around $60 bucks, and you also may be subject to a lot of additional fees."
Those additional fees could include up to $45 for each piece of checked luggage, up to $40 per carry-on bag if the airline has a weight restriction and $1 to $199 for a reserved seat.
However, there are ways to get a great deal on a flight. Ideally, consumers want to book in advance and never within two weeks of travel, Marks said.
Additionally, take advantage of alerts that many airlines and travel sites let travelers set up to track fares.
Also, time your purchase.
"Experts tell us there really is a best time to book, and that's at 3 p.m. EST on a Tuesday," Marks said. "Believe it or not, that's when the greatest number of discount seats hit the market."