Take a look a little further down the main page for the Alaska Port Chat section. There are tons of posts and see if you find something you like. Then you can Google the ports and find some operators and you can compare the prices to the tours from the cruise line. In most cases the difference is $20-$30, sometimes a little more. Whale watching, helicopter rides, dog sledding, etc., are not going to be inexpensive. Victoria I highly recommend Lake Louise, and Banff (depending on time). Seattle I highly recommend visiting the Space Needle, having some fantastic food near the wharf,and maybe exploring Pueget Sound or the San Juan Islands (if time permits).
If you're not using a travel agent, it will take a little finger work on your part, our Alaska Port Chat section is a great place to begin. Then a hop over to Google to pull up information on what you've found, or maybe some of us on the board can answer more specific questions.
We'll try to help as much as we can.