Put a test order through the store while you're setting everything up and keep track of every place where you still have to step in manually. That gives you something concrete to judge before you start loading hundreds of products. You can read about BigCommerce dropshipping here: https://easync.io/articles/bigcommerce-dropshipping/ . Pay attention to how pricing rules are handled across a larger catalog and whether the apps you need have product or order limits. Then add up their monthly fees, ...  morePut a test order through the store while you're setting everything up and keep track of every place where you still have to step in manually. That gives you something concrete to judge before you start loading hundreds of products. You can read about BigCommerce dropshipping here: https://easync.io/articles/bigcommerce-dropshipping/ . Pay attention to how pricing rules are handled across a larger catalog and whether the apps you need have product or order limits. Then add up their monthly fees, because several small subscriptions can change what the store costs to run.  

The platform is only half the equation here because a lot depends on what your suppliers can actually send you. Before you build out the catalog, check which suppliers already work with BigCommerce and how often their stock and variant data gets updated. I'd also ask how quickly they ship across the US and what their return process looks like. A supplier with messy inventory data can create more work than the store platform itself.