the problem i have with dopshipping on shopify is i have yet to find an app that calculates shipping charges from different vendors.we list over 6,000 items and most come from our central warehouse but we also use a manufacture as a dropshipper on the other side of the country. i have not been able to find something that calculates shipping charges from 2 different places. it will only calculate shipping based on one location. shipping in canada can vary quite a bit depending on where the product starts......any help or suggestions would be great.