I lived in the Lower Mainland area for a long time ( until a few years back) , and I've never heard of a GIJOE-specific convention, or even a dedicated swap meet being held.
There are toy shows and collectible swap meets that do happen, I think they still run out of the Croatian Cultural Centre, and sometimes there's some at Heritage Hall on Main, both in Vancouver--and these sometimes do feature GIJOE items for sale. You'd probably have better luck with toy shows south of the border, in the Seattle area, like the old Kent Commons shows. I think the main reason there's a lack of them is due to a very small collector population ( for GIJOEs etc.) based there, a reason often cited by the GIJOE Club as why they won't host a national convention in the Pacific Northwest.