Not only do airlines charge for checked bags, the costs go through the roof if those bags are overweight or oversized. For the first checked bag, Delta charges $23 if paid in advance online, or $25 if paid at the airport; other airlines charge similar prices. (A few exceptions: Southwest Airlines lets you check a bag for free and some airlines, including Delta, wave first-bag fees for people who carry an airline-branded credit card and pay for tickets with the card.) A second bag would cost you $32 or $35. Bring in a bag weighing more than 50 pounds, and you'll be charged $90 -- unless it weighs more than 70 pounds, in which case the charge jumps to $175. A bag that measures more than 62 inches overall (add the length, width and height) will run you $175; if it's more than 80 inches, you'll want to just stay home: the charge is $300.
Flickr user: GenBug