The one big disadvantage to this way is the owner of this small company only travels both ways once a day.
The cost is $50 one way and that includes your ferry ticket and the shuttle takes you right onto the island here. If your timing for flights is right the easiest, most direct way to get here to SJI without a car or flying from Seatac would be The Island Airporter at. Kenmore Air takes you by van from SeaTac to one of their terminals (Boeing or Lake Union), where you board a land or seaplane bound for Lopez Island for Eastsound, Rosario Resort or West Sound on Orcas Island, or for Friday Harbor or Roche Harbor on San Juan Island. From SeaTac, the shuttle leaves from Door 00 next to baggage carousel #1. The Airporter Shuttle has daily round-trip service between SeaTac Airport, downtown Seattle, and the Anacortes ferry terminal and as can be seen online by looking at their schedule at they leave SeaTac and arrive at the Anacortes ferry many times in a day, not just twice as shown on this scedule.