I once scoured the CBSA site and thought under "gambling supplies" or something similar I had found a category that the chips could maybe fall under if we fought it, where the amount was very low compared to other categories of product I'd gotten before.
Due to NAFTA, we only pay "duty" on goods that are not produced in the USA or Mexico. Given all chips from CPC, Paulsons etc. everything except China Clays is produced in North America, we should not pay duty on those items. We should be paying GST and PST as well as brokerage fees, but technically not duty.
Also , if you have a postal box in the USA, if your purchases are over your daily limit or the limit of the trip, you will pay GST and PST as well. You will save the brokerage fee, because you are technically the broker, but no duty if you can prove the goods are produced in the USA.