We at Web Access recently worked on a project where the requirement was to have an integration between CiviCRM and Drupal Commerce module.
Fortunately for us, there is already Commerce CiviCRM module that matched our requirements. However after implementation we found that it didn’t work with the latest CiviCRM version 4.7.x. So we took on the task to upgrade it to work with CiviCRM 4.7.x.
You can find the working code at https://github.com/kurund/commerce_civicrm. In my spare time I will try to verify and tackle open issues reported on this module.
I have also created an issue for asking to merge this code to the main stream https://www.drupal.org/node/2806529
Hope this helps for folks looking for the same.