Since your orders will come from several marketplaces, look for a provider that pulls them into one dashboard and updates inventory across every channel. Otherwise, you could sell the same last item twice and end up canceling one of the orders. Once a few products start selling regularly, ShipMonk could work well because it supports eBay, Amazon, Walmart, and Shopify. New products can stay with their original suppliers until there’s enough demand to keep them in a warehouse.