Not sure how much of a bargain it is, but there is a Park 'n' Fly. Here's the website...
http://www.parknfly.ca/vancouver.html
So are you only cruising one way and then flying back from somewhere in Alaska? Usually the cruises start and end in Vancouver.

While many Alaskan cruises do start and end in Vancouver, many others are one way from Vancouver, particularly those with Holland America lines.

Thanks, I'll check the site. Ours is a Princess northbound, one way from Vancouver to Whittier.

Usually the long term parking lot is less expensive than Park n Fly. If you are planning to spend the night in Vancouver at one of the airport hotels you might want to check if they have a stopover rate that includes parking. Usually if you stay 1 night you get a week of free parking. If you sweet talk them they may give you more, or have a weekly rate for the extra weeks

long term airport parking is a surface lot, with a shuttle to the main terminal. The weekly rate is about 45 bucks. Another option is getting a cheap rate at a airport hotel, say 89 bucks a night, that has free parking, but at most you will get two weeks free and have to pay for the third, but it would be less than three weeks just parking at the airport.

The cruise ship leaves from downtown Vancouver, which is about 30 to 45 minutes' drive from the airport There is long term secure parking near the cruise ship terminal, but I don't know the cost. It may be cheaper and more convenient (since you are staying in a hotel downtown?) to park there or at the hotel than the airport.

Check out these two websites with some good info:
http://www.britishcolumbia.com/information/cruiseships.html

http://www.bcpassport.com/cruise_info.html