>>> we are back from breezy point in queens , new york , and as you can probably hear from time to time overhead, we're not too far from la guardia or jfk airport , a lot of flights. these days, of course it means a lot of fees from checked bags to boarding. as everybody is about to find out for thanksgiving, how the fees are adding up. our report from nbc's tom costello.

>> reporter: in atlanta today, kate was off the plane from her wedding over the weekend. on top of her $200 airline ticket she had to pay $50 extra for the bag. if it were not for her wedding, she wouldn't have gone.

>> i refuse to fall for the trap.

>> reporter: today, we learned how many fees people are paying. priority boarding, extra leg room, in-flight food, add the commissions from rental cars and hotel sales and the credit cards which earn you miles, it is all expected to add a staggering $42 billion to the airlines this year.

>> for the airlines, this is absolutely critical, they would not exist today without these fees.

>> reporter: the u.s. airway that depends the most on the fees, and spirit airlines , with most of their revenue tied to the fees, united raked in the most from the fees, $5 billion last year, roughly $38 for each passenger, followed by delta, american, southwest, who doesn't charge for bags but does charge for priority boarding and u.s. airway.

>> if the airline makes 50 on this corousel alone, they already made much more.

>> i tell them, twice the money, and you will have a good trip.

>> reporter: the airline industry tells us that the optional services allowed the airlines to keep the air fares affordable. meanwhile, air fares are up 7%, $450 on average, the time to buy, those in the know, say is now.