Hey Bram, Erika here from ShipStation. While you're looking at shipping software providers, may I suggest ShipStation? We're a web-based shipping software that offers a connection between Shopify (and a lot of other eCommerce platforms, too) and carriers like USPS, UPS, and FedEx, among others, so that you can easily print labels. (USPS is even discounted off the retail rates and we include the Endicia account you'd need to create those labels.) In addition to that, we'll bring in all the important order information, including the shipping service your customer selected, so you don't have to copy/paste anything between Shopify and our system. We have a lot of other really cool features, too.
Perhaps the best feature (and my favorite) is the automation. You can set up hierarchical rules that will process your orders, up to the point of clicking "Print Labels" so most of your decision points are done for you.
I won't go on and on here, but we'd love to show you how ShipStation can work for your business. :) You can find us on Twitter, Facebook, or give us a call @ 512.485.4282 or shoot us an e-mail.
- Erika, Marketing Manager @ Shipstation