Spending money on the ferry might put off some frugal types but visiting your property and putting in the water on the island side would be the more rewarding kayak experience. Plus a weekend couch surfing or tenting somewhere and visiting the island farmers markets screams the ER lifestyle. Part of why I moved from SK to Van Island.
Going as a foot passenger on the ferry is usually pretty cheap - $5-$10 each way depending where you're going. Party at jon_snow's island place? LOL
It's $16 per person walk on for most ferries, $12 to Salt Spring. Some of the smaller ones may still be $10 (Denman, maybe??) The good news is that transit is great on the vancouver side, and into Victoria, and Sechelt. Otherwise the bus charters start to set you back $40 to $75.
With transit, Ferry walk ons and two people, you can expect to spend $75 easy for a round trip day. So I budget for it, it is not "Cheap", but maybe "value priced" and we rarely go unless a special trip... taking kayaks would cost a lot more, as it is hard to get a kayak on a bus. (LOL, I would love to see someone try that one!)
Ferries are not cheap! We finally returned from our camping "trip of a lifetime", over 2+ weeks, and spent $1800 on Ferry fares alone (Two ferries, family of 4). I felt very extravagant. It did include Prince Rupert, so not the normal ferry trip.
I may be game for a kayak (flat water) trip locally on the vancouver side. Ladner is supposed to be nice, or of course all those areas around Burrard Inlet.