If you can't get a used one they can be ordered on line. A good source in Seattle for paper charts is Capatain's Nautical Supplies.
You can also get one of the big chart books covering the area. While we have all the individual charts for the region on the boat we also have the chart books for the San Juans, Gulf Islands, Sunshine Coast and Desolation Sound. The books are far more conenient to use as they sit on a chart board to the left of the helm made for the purpose (photo).