It's $75 per person in Whittier and $18 in Vancouver... that is why you are getting differing prices.
It is about an hour and a half drive from Whittier to Anchroage.. You will actually dock in Whittier about 11Pm or midnight and you will be off the ship by 8AM. Odds are that your flights will not leave until late in the day but if you can get one for 11Am or 12Am, that is VERY doable.
We rented vans in Whitter and drove to Anchroage. Renting allowed us to see the sights, stop at the animal reserve etc... AND it was cheaper to rent the van then pay for 4 people on the transfer. They WILL check your bags at the ship (they have airline agents at the port) and truck them to the airport, so you do not have to worry about dragging your luggage all over with you.
Hope that helps.. write back if you have more questions.
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