It was $6 admission to the event, same as the usual entry fee (annual membership is only $20, I probably should have paid for that instead!).
The first event was a Shinto blessing by someone from the Tsubaki Grand Shrine in Granite Falls, WA (who knew there was a Shrine in Granite falls!?). Unfortunately, it took place just outside the garden rather than inside the garden due to concerns about the weather (it was not a nice day).
After that, we just explored the garden!
If you are interested in Japanese gardens and live near Seattle, I hear the Kubota Garden in South Seattle is also fantastic (and free).