Order an Evergreen Atlas from West Marine--the charts in there are fairly current, and there aren't a lot of changes from year to year. The NOAA charts are obviously the best source, but they're unbelievably expensive, but West has those, also.
What part of the San Juans? That's one of my favoritist vacation spots. Read about my own adventure in my 19' Sea Ray--The Ultimate Small Boat Adventure, $15.95 at Barnes & Noble, or can be ordered by other book stores--24 days and nights on the boat, with my Golden Retriever Maggie as my companion, through the San Juans, the Gulf Islands, the Sunshine Coast to Desolation Sound, Princess Louisa, and other points north. We've also chartered a 32' Nordic Tug twice and toured the San Juans and Gulf Islands, and made another trip to Princess Louisa (which incidentally is without any doubt the single most beautiful place on Earth).
"I have slipped the surly bonds of earth..., put out my hand and touched the face of God." J.G. Magee