Just got my 3x 13oz tanks refilled at Ambush Paintball. Super nice people, and they do a proper job (vent, fill liquid, etc.) however they suggested phoning ahead to see if they have CO2 before coming.
+1 (604) 812-2379
It was $5 for 13oz, a bit more for 20oz., and $10 for 24oz.
They can also...