Here in BC you don't often see the words "cheaper" and "ferry" in the same sentence, but for once they belong together.
During certain hours this summer, BC Ferries will reduce the cost per foot for longer vehicles and trailers on two of its routes: Tsawwassen (south of Vancouver) to Swartz Bay (Victoria), and Tsawwasswen to Duke Point (near Nanaimo on the mid-Island).
Escapees taking advantage of this deal will likely need a campground reservation when heading to the Island, since most of the eligible sailings are 4pm and later. A nice circle route would be to go over via one route, explore the Island, then come back on the other.
Reservations are advised, as summer volume can be unpredictable.