Kraus,
I have been to MOJAM three times, it is definitely worth attending.
Another option, and a little closer to Vancouver, is the first MTJAM (Montana Selfbow Jamboree) being held on the weekend of June 30, July 1 & 2 in Three Forks Montana. The Oklahoma Selfbow Society is helping us with the bow wood and instruction for the initial event. If you want Osage, bring some yew as these guys are looking to trade for some.
Hopefully there will be enough attendees to justify making it an annual event.