Exploring Subdomain Setup for Online POD Stores on Shopify

Hey guys, I have a growing number of clients that are wanting online POD stores hosted through my company. In that past we've just done pages hosted on our shopify site (ie. Quokkaprints.com/CustomerStore) but we are wanting to move more towards having the store be setup as subdomains that utilize the shopify api for checkout (ie. Customerstore.Quokkaprints.com). We think it just looks a lot clear and more legit. Does anyone have any experience doing something along these lines or recommending talking to anyone?