I'm looking to take a cruise in the next year or so. Found an awesome deal. The ship departs relatively close to where I live, and ends up in South America. But, when I was looking at flights, I found it's much, much cheaper to book a round trip to South America than it is to book a one-way flight home. The round trip is about $850, while a one way is about $1300. I don't fly much - is this common? Is there any reason I can't just book the round trip and use only one leg of it? Can I bank the unused leg and use it toward a future flight? It just defies all common sense.