Ticket scalping is also illegal. However, last week when I was in NY and wanted to attend a sold out Knicks game I bought the tickets from a guy on the street. Was I taking a risk? Yes. The tickets could have been fake. However I was willing to take that risk for a chance to get into the game.

The same thing applies with airline tickets. If the lowest fare for the dates I want to travel is $800 and someone on Ebay is selling an AA roundtrip ticket good for anywhere for $400, it only makes sense to buy the Ebay ticket.

The seller obviously isn't going to tell the airline that they sold you the ticket so I don't see the problem.

BTW, I have never purchased a ticket off of Ebay but I definitely would consider it if the fare was outrageous for the dates I needed to fly.