Airfares to Alaska are not inexpensive, and that's why I used FF miles for those trips! You can get an idea about airfares by checking June 2013 "multi-city" routings on
www.kayak.com from your home airport to Anchorage, and from Vancouver (or Seattle) to your home.
If you choose to do a one-way cruise, I
strongly suggest you allow at least a few days to see some of the Alaskan interior. At a minimum - I would fly to Anchorage, rent a car, drive to Denali National Park (about 5 hours) for 2 nights, then drive back to Anchorage. Princess sails out of Whittier (about 1.25 hours from Anchorage), and HAL, RCI, and Celebrity sail from Seward (about 3 hours from Anchorage).
The Alaska Ports of Call board at Cruise Critic has a lot of info:
http://boards.cruisecritic.com/forumdisplay.php?f=55