Props to Fluidseal! I've been there 4 times now and 3 of the 4 times, they didn't charge me for the o-rings I bought (or should I say borrowed).
It's one of those "in the back of the industrial park" places that you'd never think to go. But if they don't have that o-ring or gasket you want, they'll make it for you.
Fluidseal, just off Bridgeport in Rchmond, BC.