Transportation options -Cruises

I had the bright idea that we may be able to catch a cruise to Asia for less than the cost of an airline ticket.  I could not find anything leaving soon, but I did learn this:  Some cruise lines offer cheap passage on re-positioning cruises.  This type cruise will  have more days at sea and less days in port, but it is still a cheap way to go.  I found one from Asia to Australia for $800 which I am sure is cheaper than air.  It is definitely something to think about when I want to move on to a new place.