Be thankful that all you got was "ripped off". There is a family in our neighborhood that went scootering on one of the islands and the mother got into an accident and had to be medivac'ed to the states to save her life. She is ok now, but I bet she never does that again.
I ride a Harley in the states, and it still scares me to see people get of the cruise ship and start riding scooters on some of those islands. It really isn't a matter of how good a driver you are or aren't, you are in a foriegn country with entirely different driving habits and norms. Cozumel isn't too bad, but be careful!
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007