Um. No it isn’t. Appx 90 miles to colchester. 80 miles to Sherbrooke. Drive time Sherbrooke Costco is faster - however - as someone else pointed out, after taking the crossing time into account - it is likely a wash. I would add that in addition there are certain items restricted at the border and quantity of some items may require paying a tarif. Personally I would just find somewhere local to shop. Especially for food.