Use Contact Seller.
Tell the seller the items that interest you. Ask how much he would charge to ship TO CANADA and by USPS/Canada Post. Tell him that you do NOT want him to use the Global Shipping Program which charges buyers a substantial premium over Canadian Border Security Agency fees.
If the shipping is satisfactory, order your three items. You can use Contact Seller to remind him of the agreed shipping fee and that you require USPS shipping, not courier.