By showing them proof of your value. Demonstrate your results. The ROI must be clear for your prospect. My general rule of thumb for demonstrating value to service-based business prospects is between 6–10x. Any less, and the "indifference lever" won't budge.

Here's an example I use in my own collateral.

As part of my Core Marketing Message, I firstly describe the target audience, secondly describe what the benefits are; and lastly, describe the results:

Smarthinking helped Greg Pike reposition his firm as an SMSF Audit specialist. Collins Pike Accountants got an ROI of more than 1900% and won over $30,000 of new business from a single campaign.

I don't ever get quibbles over my fees.

Which of course could mean I'm not charging enough, but that's a whole other story!