Business–whether for- or non-profit–is always about an exchange of value. Mary gives Sam a quilt in return for which Sam gives Mary $75 or a year’s supply of cucumbers or something else Mary wants.
Reciprocity and balance–the basic law of the universe–are thus the foundation of business and the trust that makes business possible.
I’ve written a few books about this. Here are some links:
Professional Ethics for Managers
The Morally Responsible College