Give the gift of Drupal. All merchandise is 50% off through 2016.
This module adds a basic line item type to Drupal Commerce. This line item type should be used by admins to add arbitrary price amounts directly to orders without needing the use of products. e.g. Adding a payment order to a user account manually after the user paid in person. I could not find a similar project, but I might have missed one if it exists.
This module also updates the Commerce Line Item view to display the added amounts to the table.