I just recently returned from a CCEO (Chamber of Commerce Executives of Ohio) Retreat and heard an excellent quote from our speaker regarding non-members or non-customers. Instead of "non" anything, change your perspective. I switched from calling a business a non-member to a potential member a few years ago, but this is even better:
Non-Member - negative thinking
Potential Member - better thinking
Future Member - positive thinking
How do you look at your non-clients/customers?