Hmmm, I have neve reheard of them but that website is awful, very hard to know what you are getting, they do seem quite expensive.
Have you ever heard of a repositioning cruise? where say a Carnival boat is in Malaysia and it is going to now be stationed in Seattle, they sell tickets fairly cheap because it is a one way trip and they have to take the vessel anyways, so they try and fill it up with people, these are usually much longer cruises than normal.