Working with a team of 4 developers, we were able to develop a new platform for Store.USGS.gov. The backend is powered partly an SAP Enterprise solution and was the most tricky part of this build. By doing some research, I was able to determine that there needed to be a web services endpoint for us to access in order to feed the products into Drupal. Unfortunately, this required some significant updates to their servers and took much longer than anticipated. Having said that, the updates were made and we continued to build out features for their new site.
The end result is a very robust and stable commerce site based on Drupal Commerce and highly customized.