Try Pender Hbr, Powell R, Lund, Campbell R, Quadra
There are a number of towns on the way with docks, stores and facilities. eg: Pender Harbour, Comox, Westview, Powell River, Lund, Campbell River...You might try looking in the Ports and Passes book (buy it in any marine store in northern WA or BC) or the guide published annually by Pacific Yachting magazine, or Charlies Charts, or the Dreamspeaker guides....It's a fact of life that supplies are more expensive in small towns -Canadian or otherwise- and the reasons for this should be obvious.By the way, you might want to think carefully about how you're going to deal with your garbage, and where you're going to get fresh water when you're up here.Population is sparse, soil is thin, there are few landfills -and the economy is dependent on seasonal tourism dollars, so there's little infrastructure. I hope you enjoy your trip.