Amusingly the prices of the seaplane (if you get the super-saver version) ends up being $180 for two vs. $107 for two people (or 110 vs. 90 for one)[1] which is a pretty depressing highlight of just how overpriced BC Ferries is (possibly due to running such large vessels).

1. Both of these assume you're boarding the ferry with a vehicle which I think is a fair assumption given how insanely inconvenient the ferry terminal is.